What is InsideProject Reports

Sites ............................................................................................ 2

Instrument .................................................................................... 4

Data System ................................................................................ 7

Management................................................................................. 9

Data Management and Analysis ReviewPanel Report ................................................................................11

Project Response ........................................................................14

Team ReportsData Reduction and Analysis ......................................................16

Models .........................................................................................16

Inversions ....................................................................................19

Magnetic Effects ..........................................................................19

Mode Physics ..............................................................................20

Low Frequency and Nearly Steady Flows ...................................20

DMAC Users Committee ..............................................................21

Time Series Interpolation Schemes ..........................................22

Hare and Hounds ...........................................................................23

Data Distribution and Publication Policy .................................25

GONG ’92 .........................................................................................27

GONG ’94 .........................................................................................31

Visitors .............................................................................................32

Theses ..............................................................................................32

Recent Publications ......................................................................32

Position Available ..........................................................................33

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GONG

33333333333333333333333333GONG Newsletter33333333333333333333333333

Number 19 The Global Oscillation Network Group November, 1992

3333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333Just when you thought that it was

safe to go back to your mail box, hereis yet another GONG Newsletter. Yes,it has been a long time, but have weever accomplished a lot!

Among other delights that the seri-ous reader will discover inside is thegood news that we now have an instru-ment that we can properly calibrate,produces excellent data, and magneto-grams to boot. We have made veryconsiderable progress in getting thedata management and analysis centerdefined and under development, andwe have even done some preliminarymerging of imaged helioseismic data— just artificial data for the time be-ing; we don’t have the network run-ning yet after all. We have five of thesix site Memoranda of Understandingsigned and sealed, and there was avery well attended ( 100+ participants )and worthwhile “GONG ′92” meetinghosted at the High Altitude Observ-atory.

Data from the prototype instrumenthas proven to be scientifically interest-ing and publications are already start-ing to appear. You will find the“GONG Data Distribution and Publica-tion Policy” that we discussed at lastyear’s Annual Meeting in this issue ofthe Newsletter. Please do read thissection, starting on page 25.

We continue to make good progressand are hopeful that network opera-tions can start in 1994 — 24 monthsfrom now — if our funding is main-tained as planned. All of this thanksto the outstanding efforts of a dedicat-ed project team and the suggestionsand work of many, many members ofthe community. We have conducted anumber of external reviews of theProject’s activities, including one ofthe overall data system that is discuss-ed in this Newsletter, and we are plan-ning another major one in the near

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future of the overall instrument pro-duction and fielding plan. We want tothank the members of the ScientificAdvisory Committee [ Peter Gilman,Bob Noyes, Alan Title, Juri Toomre( chair ), and Roger Ulrich ], the TeamLeaders ( particularly DRAT leaderTuck Stebbins who chaired the DMACreview and now chairs the DUC aswell ) and the members of the ad hocreview committess, and many otherswho continue to contribute their exper-tise and energy.

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Next year’s GONG Annual Meetingwill take place here in Tucson, April19-21, and we will send you more in-formation concerning it in the next is-sue of the Newsletter which will “goto press” on January 15, 1993. We in-vite you all to submit your contribu-tions for inclusion. John Leibacher

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Calendar

Event Date Location and Contact222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222Neutrino Astrophysics December 29, 1992 -

January 7, 1993Jerusalem( John Bahcall & Steven Weinberg )222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222

Annual GONG Meeting April 19-21, 1993 Tucson( John Leibacher )222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222

Advances in Solar Physics May 11-15, 1993 Catania( Peter Hoyng )222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222

Mid-May, 1994Helio- and Astero-Seismology from the Earthand Space

Los Angeles( Roger Ulrich )

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Project Reports

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Sites

The site survey instruments continueto operate at the selected sites, andthey will provide baseline data up untilnetwork operations commence.

The project has now concludednegotiations with the host institutionsof five out of the six field sites, andtalks with the sixth site are proceedingsatisfactorily. Formal memoranda ofunderstanding have been signed withCerro Tololo Interamerican Observ-atory in Chile, Big Bear Solar Observ-atory in California, Udaipur Solar Ob-servatory in India, the Institutod’Astrofısica Canarias in Spain, andthe Learmonth Solar Observatory inWestern Australia.

The Udaipur MOU was signed byProfessor R. K. Varma, Director of thePhysical Research Laboratory, in aceremony in Ahmedabad in February.The Spanish MOU was signed by Pro-fessor Francisco Sanchez, Director ofthe IAC, and Goetz Oertel, Presidentof AURA (NOAO’s corporate entity) inMay at the IAC headquarters on Tener-ife, in the presence of Marisa Tejedor,Rectora of the University of La La-guna, and other dignitaries. The Lear-month MOU was signed in September

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in a ceremony at Parliament House inCanberra. Senator Nick Bolkus, Min-ister for Administrative Services,signed for Learmonth, while Jim Ken-nedy represented AURA/GONG.Members of the U.S. diplomatic dele-gation, David Cole, Director of the IPSRadio and Space Services, and othernotables participated.

The project is continuing to nego-tiate with the National Oceanic andAtmospheric Administration for accessto the High Altitude Observatory siteon Mauna Loa in Hawaii.

( Incidentally, the recent earthquakecentered near Big Bear has not upsetplans to deploy the first field station tothat location during 1994. )

On another front, the GONG Projecthas decided not to place a seventh in-strument at the Urumqi AstronomicalStation in China. The decision wasmade after studying the differences inperformance between the seven-siteand the six-site network windows, andestimating the impact of these differ-ences on the scientific goals of theProject. The scientific impact was as-sessed by examining the effect of thewindow spectrum sidelobes on the re-latively strong p modes and the effectsof the window spectrum backgroundon the much weaker g modes. In allcases, the six-site network performedcompletely adequately. Indeed, spatialleakage due to the limited accessiblearea of the solar surface is likely to be

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much stronger than any residual tem-poral leakage.

The impact of the fundamental diur-nal sidelobe is addressed first. Sincethe sidelobe power is proportional tothe power of the mode associated withit, the largest effects will appear in theregion of the p modes. The height ofthe first sidelobe was thus estimatedand compared to the solar backgroundnoise surrounding the p modes. Toquantify this, consider an average pmode with an amplitude A of 5 cm/sand a width W of 1 µHz. The powerspectral density of this mode is A2/W =2500 (m/s)2/Hz. Analysis of the ob-served six- and seven-site networkwindows shows that the height inpower of the first diurnal sidelobe rela-tive to the main component is about4×10-4 for the six-site network, and1×10-4 for the seven-site case. Thus, anaverage p mode will be surrounded bysidelobes with a height of 1.0(m/s)2/Hz in the six-site case, and 0.25(m/s)2/Hz in the seven-site case.Measurements of the solar backgroundnoise in this region are about 16(m/s)2/Hz (Jimenez et al. 1988, Astron& Astrophys. 192, L7), thus the diur-nal sidelobes for the six-site windoware more than an order of magnitudesmaller than the solar noise in this re-gion of the spectrum. While the abso-lute improvement in sidelobe perfor-mance of the seven-versus the six-sitenetwork is a factor of four, relative to

- 3 -33333333333333333333333333the background the performance of thesix-site network is completely ade-quate in this regime.

Next, the impact of the overall back-ground of the window spectrum is as-sessed. A low background is desirablefor the detection of very low-ampli-tude low-frequency modes, such as gmodes. Again, the approach is tocompare the estimated effects of thewindow spectrum and the solar back-ground noise. Since there are no con-sensus measurements of the propertiesof g modes, the estimate was done us-ing a hypothetical g mode with A = 1mm/s, and W = 0.1 µHz, giving apower spectral density of 10 (m/s)2

/Hz. The power spectrum of the six-site window shows an overall averagebackground power density of 7×10-6

relative to the main component; for theseven-site window, the value is 5×10-6.Thus, the background power densityproduced by the hypothetical g modewould be 10 × 5 × 10-6 = 5 × 10-5(m/s)2

/Hz for the seven-site network, and7×10-5 (m/s)2/Hz for the six-site net-work. However, since the backgroundis broad-band unlike the sidelobes, it isnecessary to consider the combinedoverlapping background from several gmodes. Theory predicts about 20 gmodes within 60 µHz at a given l inthe more crowded regions of the g-mode spectrum. The combined back-ground power for such a set of modeswould thus be a factor of 20 higherthan for a single g mode. Thus, the to-tal g mode regime background causedby the interaction of the g modesthemselves and the window function isestimated to be 1.4×10−3 (m/s)2/Hz forthe six-site network, and 1×10-3

(m/s)2/Hz for the seven-site case.These levels are much lower than boththe measured average solar back-ground of 1200 (m/s)2/Hz in the 100to 160 µHz band, and the 10 (m/s)2

/Hz power density of the hypotheticalg mode. The performance of the six-site network is again completely ade-quate in this calculation.

The window spectrum is replicatedaround every point in the solar

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spectrum, regardless of whether thepoint contains power from a mode orfrom the solar background. It is there-fore also necessary to estimate theamount of additional noise that wouldbe created in the g mode regime by theinteraction of the solar background, asopposed to the g modes, with the net-work observing window. As statedabove, the average solar backgroundnoise power density is measured to be1200 (m/s)2/Hz between 100 and 160µHz, and the relative background ofthe window functions are 7×10-6 forthe six-site case, and 5×10-6 for theseven-site case. For a one-month timeseries, there are about 156 frequencypoints in a 60-µHz band, each sur-rounded by the window spectrum.The total noise added by the windowis then roughly

The above results were obtained us-ing windows that had been observedwith the GONG Site Survey Instru-ment. However, the Site Survey In-strument is far less complex than theDoppler science instrument. In aneffort to predict the future performanceof the network with a more complex(and hence possibly less robust) in-strument, and to assess the impact of aseventh site in this situation, the ob-served downtime was systematicallyincreased at each station by factorsranging from two to ten. The networkwindow was then constructed and ana-lyzed in the usual manner. This studyshowed that the six-site network issatisfyingly robust, even in the ex-treme case of a tenfold increase intime loss. In the worse case, the frac-tion of observing time was 85.88%,and the height of the first sidelobe inthe power spectrum increased to 0.2%,still far below the sidelobe height in asingle-site window. For comparison,the six site survey instruments achiev-ed a combined observing time fractionof 93.63%, and a sidelobe height of0.04%. To assess the impact of thedegraded networks on the science,consider the worst case of a tenfold in-crease in downtime. Then the relativepower of the first sidelobe rises to

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2×10-3 for the six-site network, and to1.4×10-3 for the seven- site network.Performing the same calculation asabove results in an estimate of 6(m/s)2/Hz for the six-site sidelobeheights around the p modes, and 4.2(m/s)2/Hz for the seven-site sidelobes.These numbers are to be comparedagain with the 16 (m/s)2/Hz level ofthe solar background. Once again, thesix-site network performs adequately,even in this scenario. For the g modecalculations, the relative backgroundpower rises to 2×10-5 for the six-sitenetwork, and 1.7×10-5 for the seven-site case. This results in an estimatedg-mode background due to the modesof 4×10-3 (m/s)2/Hz for the six-site net-work, and 3.4×10-3(m/s)2 /Hz for theseven-site case, both still far below the10 (m/s)2/Hz g-mode power density.The estimated additional noise due tothe interaction of the solar backgroundand the window function rises to 3.8(m/s)2/Hz for the six-site case, and 3.2(m/s)2/Hz for the seven-site case. Allof these estimates are substantiallybelow both the 10 (m/s)2/Hz of the hy-pothetical g mode, and the 1200(m/s)2/Hz estimated level of the solarbackground in the g-mode regime.Again, the six-site network is seen toperform adequately.

The impact of adding a seventh siteto the network can also be assessed bydetermining the amount of additionalobserving time that would be gained.The amount of additional observingtime provided by the Chinese site canthen be compared to the amount pro-vided by any other single site. Thiscan be done by constructing the win-dows for the seven-site network, andalso for the six six-site networksformed by eliminating a single station.The differences of the filling factors ofthe windows can then be used to com-pute the number of days that a singlegiven station is the only one observ-ing. On a yearly basis, it was deter-mined that the Urumqi site was solelycarrying the entire network for a totalof 4.38 days. It was also determinedthat the other six sites solely carried

- 4 -33333333333333333333333333the network for periods ranging from7.88 to 23.03 days per year, with anaverage of 15.85 days per year. Thus,the Chinese site carried the network afactor of three less time than the aver-age of the other sites.

These results have led the Project toconclude that the addition of a seventhsite at Urumqi is not cost-effective.While the network window wouldindeed be improved, the six-site win-dow is entirely adequate for the pro-ject, and the additional expense infunds, personnel, and data-reductioneffort is not justified. It should be not-ed that this decision has been basedentirely on consideration of the in-tegrated performance of the GONGnetwork as a whole, and should in noway be construed as indicative of theutility of Urumqi as a site for other as-tronomical purposes.

The GONG Project would like toextend its warmest thanks and appreci-ation to the Urumqi group, particularlyXiao Suming and Huang Zhen, whohave played very important roles in thetesting of the Urumqi site. Because ofthis substantial contribution to the Pro-ject, the Urumqi personnel are con-sidered to be permanent members ofthe GONG Project, with full access tothe future data products.Frank Hill and Jim Kennedy33333333333333333333333333333333

Instrument

Since the last Newsletter, the princi-pal Project effort has shifted fromdevelopment of the prototype to pro-duction of the final instruments. Car-penters and electricians have beenbusy converting six shipping con-tainers into GONG field stations. Thiswork continues in the GONG stagingarea adjacent to NOAO’s main parkinglot in Tucson. A crew made up ofmembers of the NOAO Central Facili-ties Operations group and temporaryhelp has nearly finished the work. Anew site has been identified for use asan integration area when the field

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shelters are mated to the production in-struments, and tested prior to deploy-ment. The University of Arizona hasagain cooperated with the project, leas-ing a small plot of land within theAgriculture Department’s CampbellFarm facility, six km from the NOAOoffices. The shelters will be set upside by side for final assembly, testingand cross calibration of the field in-struments.

A computer-controlled milling ma-chine is running two shifts to producethe field instrument mechanical parts.Its first task was to make parts for thelight feed systems. The productionshipment of mirrors for the light feedswas received recently, tested for prop-er polarization performance and foundto not meet specifications. The vendoridentified a problem and the mirrorsare being recoated. The second majortask is to produce parts for the bire-fringent filter and the ovens. This taskis nearly completed. At the sametime, necessary lathe work is beingdone in parallel at NOAO and anumber of tasks have been contractedto outside vendors. A filtered-air, op-tics assembly bench has been set up ina temperature and humidity controlledroom at NOAO that was once used forruling large gratings. During the nextthree months we expect to assemble allthe birefringent filters and spares — adelicate task since each one consists of25 pieces of crystal optics that must beaccurately aligned.

The vendor of the Michelson inter-ferometers that are the heart of theGONG instruments expects to deliverall of the production units by late Nov-ember. We will carefully test thesebefore installing them in the field in-struments early next year.

Similar intense efforts are underwayto produce the final electronic systemsand computer programs required forthe field instruments. Both of thesejobs are large since careful documenta-tion and checking are required. Forexample, more than 1000 separateelectronic tasks appear on the projectplanning charts. Proper timing and

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synchronization of the GONG observa-tions has occupied both the electronicand software groups. It is our currentplan to take data synchronized with themeasurements to be made with theSolar Oscillations Imager to be flownon SOHO. As we anticipated, a com-mercial replacement for the Omegatime signal receiver became available.The new system is based on signalstransmitted by the Global PositioningSystem (GPS) satellites. The new re-ceiver has been working well sinceinstallation at the GONG prototypeand it provides more than enough ac-curacy for our needs.

The prototype instrument has beenwaking itself every morning since ear-ly in 1992. It has been quite robust inmost aspects. For example, we havehad no problems at all recording thesolar data on Exabyte tapes this year.The instrument survived the hot Tuc-son summer and our thunderstorm sea-son with only one significant problem:the air conditioner clogged with ice ontwo occasions. One time was due to aloose piece of paper sucked into the airintake port. The second time is still anunsolved mystery. The productionfield stations have two redundant unitsto protect against problems of this sort.The backup power generator at firstwas not as reliable as we would like.Subsequent work has improved its reli-ability, and a program of weekly exer-cise makes sure that it is ready to startwhen needed.

Instrument development work cen-tered in three areas since the lastNewsletter. An intensive effort to re-place our baseline CCD camera with aTexas Instruments model havingsquare pixels was not successful. Allcharacteristics of the camera were ex-cellent except for its linearity. Thisappears to be a problem with the CCDitself which is a surprise since thesame architecture is used in the base-line CCD camera that has excellentlinearity. A similarly vigorous effortwent into producing a stable laserreference signal. By using a dual-fiberscrambler and a rapidly rotating dif-

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Magnetogram made with the GONG prototype instrument on August 27, 1992. Integration time was

60 seconds giving a noise level of about 10 gauss per 8 arc sec pixel.

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fusing plate, the short-term noise levelof the laser signal was brought downto about 1 m/s rms. This is about twoorders of magnitude worse than theshort-term noise of the solar signal. Itappears that a major effort would berequired to improve the laser signalthat much.

The third major development effortwas calibration of the prototype solardata. A difficult problem arose whenthe optical package was moved fromthe old GONG lab facility in theNOAO building to the prototype site.We had no problem calibrating thesolar data until the move. However, atthe prototype site, the calibrations al-ways left residual defects. After ex-perimenting with several new calibra-tion methods and dozens of opticaltests, the problem was still unsolved.We finally moved the optical systemback to the old lab but the problempersisted. The difficulty turned out tobe a bad figure on our in-house

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interferometer. In the course of theoriginal move to the prototype site, theinterferometer had been installed in thesecond of two possible orientations.This placement presented a poorlyfigured portion of the interferometer tothe active part of the optical path.When combined with limb darkeningof the solar image ( important in thecalibration mode ), this led to defectivecalibrations. Turning the interfero-meter to its first orientation improvedthe figure across the used portion ofthe aperture and the calibrations wereagain satisfactory.

After that problem was fixed, wefound what appeared to be a Fabry-Perot fringe pattern that varied withthe temperature of the air in the instru-ment enclosure. The fringe patternwas of a scale that it should have ar-isen either from an air gap of about 5mm or a piece of glass about 3 mmthick. No dimensions closely cor-responding to these numbers exist in

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the instrument. Blowing hot air onvarious pieces of optics finally re-vealed that the offensive piece was a 6mm exit window of the birefringentfilter oven. A temperature differenceof 15 K across the window distortedthe expected Fabry-Perot fringes andcaused them to change with ambienttemperature. It has been replaced witha slightly wedged window. This ap-pears to be the last significant calibra-tion problem. We expect to be work-ing on calibration improvements untilthe instruments are deployed, but thecurrent performance appears to becompletely adequate for the mainscientific goal of the GONG project.The design philosophy of deliberatelyimaging optical elements that are like-ly to cause problems has been painful.An alternative is to blur these elementsto hide difficulties. In the end, thehard choice will pay off since we havelocated and corrected subtle problemsthat could easily have degraded thesolar data after the network becameoperational.

Testing of the magnetograph capa-bility of the GONG instrument hadbeen postponed until fairly recently. Itwas most alarming that our baselinedesign, which had worked fairly wellin breadboard form, produced verypoor results. The problem was tracedto a non-uniform liquid crystal modu-lator. A different modulator producesmuch better results.

During the transition from develop-ment to production, it became clearthat all of the features that we plannedto incorporate into the instrumentcould not be ready in time for thescheduled network deployment. Thesecapabilities were examined from ascientific viewpoint, discussed with theScientific Advisory Committee andwith several Teams at the recentGONG meeting. As a result of theseconsultations, the following decisionshave been made by the project:

Stable Laser: DeletedSince the stable laser reference sig-

nal is currently about two orders of

- 6 -33333333333333333333333333magnitude noisier than the instrumen-tal part of the solar signal, and it is notclear how to improve the present per-formance by such a large increment,the laser reference will be deleted.This means that a relative zero veloci-ty point will have to be derived fromthe solar data. It also means that abreach of the hermetic seal of the in-terferometer could be a serious prob-lem. To counter this possibility, abarometer signal will be substituted forthe laser signal in the data stream. Wehave done this before so no new en-gineering is required. The velocityzero point can probably be derivedadequately by removing from an ob-served solar velocity image the ephem-eris velocity and a model of differen-tial rotation and the limb effect. Anaverage of the residual velocities,masking out active areas, should givea fairly stable reference.

5oA Filter Monitor: DeletedA real-time monitor of drift of the

5-oAngstrom prefilter will not be in-

stalled. The rationale is that the ven-dor of the filters is using a new tech-nique that should reduce drift to anegligible level. We will measure thewavelength stability of the filters dur-ing the semiannual maintenance visitsto each site.

Square Pixels: DeletedWe plan to use the rectangular pixel

cameras that have been in service for anumber of years. However, since it isover three years since we tested com-mercial cameras, and a number ofpromising models have appeared onthe market, we will run a set of testsof a few of the most promising modelsto see if a square-pixel camera caneasily be swapped for the existingmodel. Such a swap would give thebenefit of uniform resolution of thesolar image.

Camera Rotator: KeptA mechanism to rotate the camera

to follow the rotation of the solar im-age during each day has been

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designed, built and tested in the proto-type. An alternative to building sixmore of these rather complicated andprecise devices is to have a simplefixed camera mounting and let the im-age of the Sun rotate on the CCD dur-ing the day. This leads to an un-desired blurring of the images andvarying response to spherical harmonicpatterns on the solar image. Theseeffects were deemed scientificallyunacceptable, particularly in light ofthe rectangular pixels, and so the cam-era rotators will be built and installed.

Magnetograph: KeptAs mentioned above, magnetograms

obtained with the prototype instrumentwere of poor quality. This led to thepossibility of deleting the capability ofmaking magnetograms. Consultationwith the community made it clear thatthis is not a good idea. Fortunately, asimple change of modulator type hasgreatly improved the quality with verylittle design impact. We plan to retainthe magnetogram capability and tocontinue evaluation of the new modu-lator as long as this does not delayfielding of the GONG network. How-ever, we will not build a computer-controlled focus mechanism to com-pensate for the slight focus changeproduced when the modulator is insert-ed into the optical beam. An alterna-tive is to use a block of glass in nor-mal observing mode to shift the focusby the same amount. We reject thataction because of the danger of intro-ducing fringes into the solar velocitydata. Thus the magnetograms will bevery slightly out of focus relative tothe velocity data, which are alreadypurposely defocussed.

Scattered-light Detector: DeletedThe prototype instrument has a

detector to measure scattered light inthe sky beyond what can be measuredin the corners of each CCD image.This can be operated only when darkframes are taken with the CCD cam-era. Recent work has shown that evenshort gaps in the series of velocity

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images significantly compromise thequality of the oscillation spectra.Thus, fewer and shorter calibrationswill be made during an observing day.(Magnetogram observations also pro-duce velocity images and so do not in-terrupt the velocity time series). Thevalue of the distant scattered lightdetector would be questionable if itwere used so seldom as to greatly un-dersample the variations of scatteredlight. Accordingly, the field instru-ments will not have this capability.On rare occasions when scattered lightmeasurements are required, we cansimply point the telescope far enoughaway to get the data using the maindata system.

Enhanced Automation: DeferredEarly in the GONG project, the con-

cept of the instrument was similar to aspacecraft that operates itself with onlyoccasional intervention. Experiencehas taught us that operating on theground presents a wider variety of en-vironmental challenges than operatingin space. As a result, the degree of au-tomation built into each instrumentwill be modest and we will rely on hu-man operators to react to abnormalevents rather than trying to plan forevery possible circumstance. Normal-ly, each instrument will acquire theSun in the morning by itself, do cali-brations automatically, and continuedata recording during the day untilsunset without intervention being re-quired. The prototype has operated inthis manner for many months. How-ever, although equipped with severalenvironmental sensors, it is not awareor intelligent enough to know what todo in case of bad weather or other ab-normal conditions. The current plan isto rely on human intelligence to dothis job while increasing the degree ofautomation gradually and appropriatelyas experience is gained at each site fol-lowing deployment.Jack Harvey and Rob Hubbard

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A new method for accurately determining the image geometry and estimating the observationalModulation Transfer Function (MTF) for a full-disk solar intensity image has been developed by Tonerand Jefferies. The method exploits the zero crossing properties of the Hankel transform of anobserved image to recover the image’s true dimensions to better than 0.01 of a resolution element,and to reconstruct the MTF to within 5% at low spatial frequencies and 15% at high spatialfrequencies. On the left we compare the dimensions recovered using this method ( small dots with 1sigma error bars ) with the dimensions obtained using the FNDLMB function from the GRASPpackage ( large dots ) and the true dimensions (dashed lines) for a time series of synthetic images inwhich the “seeing” and “scattering” were varied from image to image to mimic rapid changes in skyconditions. On the right the recovered MTFs are compared to the input MTFs for synthetic imagesthat were computed using a Gaussian seeing model with different values for the dispersion. The x-axis is the spatial frequency relative to the Nyquist frequency. From top to bottom the dispersion is:0.25, 0.50, 0.75, and 1.00 pixel.

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Data System

During network operations, the DataManagement and Analysis Center( DMAC ) will be required to process 1GB of data per day (12 kB/s) in orderto keep in cadence with the input dataflow from the instruments in the field.The actual data processing rate mustalso incorporate a margin of 100% toallow reprocessing without fallingbehind the input data stream. TheDMAC will incorporate a pipeline ofprocessing steps, a Data Storage andDistribution System (DSDS), and on-site visitor facilities.

The data products of the DMAC willconsist of the following items:

Raw Field Data (1000 GB)Merged Velocity Images (200 GB)Day, Month & Three-Year Velocity

Time Series (1100 GB)

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Day, Month & Three-Year VelocityPower Spectra (600 GB)

Month & Three-Year VelocityMode Frequencies (0.775 GB)

Hourly Magnetograms (5 GB)Ten-Minute Averaged Velocity, In-

tensity & Modulation Images(100 GB)

The DMAC staff currently numberseleven: the Data Scientist, Data Man-ager, five scientist/programmers work-ing on the pipeline development, twodata base specialists working on theDSDS development, and two data tech-nicians. In addition, the DMAC hasgreatly benefited from the help ofseveral members of the GONG com-munity.

In May of 1992, the GONG Projectconducted an outside review of theDMAC System Development Plan. Asix-month series of internal reviewsculminated in GONG Technical ReportNo. 92-1, which describes the plan in

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detail. Copies of this Report, alongwith the Review Panel’s recommenda-tions and the Project’s responses to therecommendations, are available on re-quest. The Review Panel consisted ofTuck Stebbins (JILA, Chair), Ron Al-len (STScI), Tim Brown (HAO),Richard Grubb (NOAA/SEL), GarethHunt (NRAO), and Roger Ulrich(UCLA).

The Panel endorsed the overallDMAC plan to use multiple high-endworkstations for the pipeline, and touse Exabyte tapes as the DSDS medi-um. The Panel also had several speci-fic recommendations; here we sum-marize the more important issuesalong with the Project’s responses.( The Panel Report and the Project Re-sponse are included later in thisNewsletter. ) The Panel recommendedthat the Project choose a single vendorfor the workstations, and the Projecthas selected Sun to supply the hard-ware. The Panel thought that moredirect community input to the DMACwas necessary, and the Project has ap-pointed a DMAC Users Committee,which will be discussed more fullybelow. The Panel suggested the use ofbar codes and electronically readablelabels to identify the 15,000 Exabytetapes that will be flowing through theDSDS, and the Project has selected andpurchased a bar code reader for devel-opment purposes. The Panel also re-commended that the movement oftapes through the DSDS be minimized,the Project is currently studying vari-ous methods of achieving this. Moredetails on these and the other recom-mendations can be obtained by re-questing a copy of GONG TechnicalReport 92-1.

The Panel recommended the estab-lishment of a user’s group to providemore direct community input into theDMAC development. The Project hasorganized a DMAC Users Committee(DUC) initially composed of TuckStebbins (Chair), Tim Brown, JørgenChristensen-Dalsgaard, Todd Hoek-sema, and Roger Ulrich. The DUCwill meet 3-4 times per year, usually

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This figure shows the difference in m-averaged l = 20 and l = 100 frequencies measured fromtwo synthetic oscillation spectra. One spectrum was obtained from a time series of mergeddegraded synthetic images, while the other was created from the corresponding unmergedundegraded “perfect” images. The merging was performed by simply averaging with equalweights all available detrended remapped velocity images at a given time step. The figure showsthat the deviation is typically less than 0.25 µHz, with occasional large fluctuations that may bedue to imperfections in the simulation. The rms deviation is 0.40 µHz for the l = 20 modes,0.14 µHz for the l = 100 modes, and 0.31 µHz for the entire mode set. These rms deviations,from a single realization of a one-day time series, are a factor of five or more smaller than therandom error in frequency of 2 µHz predicted for this temporal length by Anderson, Duvall andJefferies (1990, Ap. J. 364, p. 699). From this preliminary result, it appears that a simpleaverage merge will suffice for the GONG p-mode pipeline. We are currently developing moresophisticated merging schemes with weights determined from quality measures of the data, andare constructing a better artificial data set.

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in Tucson, and the members havebeen assigned two- and three-yearterms. New members of the DUC willbe recruited from the general GONGcommunity as needed. The purpose ofthe DUC is to act as communityrepresentatives to advise the GONGData Scientist on such matters as thesetting of priorities for softwaredevelopment, science data products,user interface, visitor support, andstandards of pipeline performance.Non-DUC members of the GONG usercommunity should raise specificDMAC issues with the DUC memberswho will then channel the concerns to

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the GONG Data Scientist. The DUChad its first meeting at the BoulderGONG 1992 Meeting, and the secondDUC meeting will take place in Tuc-son in late September, early October.[ Editor’s Note: see the DUC report starting

on page 21. ]

One aspect of the DMAC plan is thedefinition of a baseline pipeline. Thisbaseline system consists of prototypesoftware functional components thatare now available, and represents theminimum state of the processing thatwill be done to the GONG data. De-velopment of baseline areas will con-tinue for the forseeable future, and we

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anticipate that enhancements will bemade to the pipeline even during thenetwork operational phase. Currently,the relevant aspects of the baselinecomprise statistical bad-image identifi-cation supplemented by visual movieinspection; no image restoration; asimple average merge either of de-trended remapped velocity images orof spherical-harmonic coefficients;peak-fitting for every value of l, m, n,but without computing spectral side-line error matrices; and the computa-tion of ten-minute averages for the lowfrequency/steady flow analysis. Thefurther development of these baselinecomponents will be prioritized in con-sultation with the DUC.

In addition to the developments dis-cussed above, the GONG DMAC staffhas made progress in several otherareas. A total of 20 days of data havebeen processed in support of the proto-type instrument development, and astudy of the overall timing and organi-zation of the pipeline has been com-pleted.

Ingres has been selected as theRDBMS underlying the DSDS, and aprototype DSDS user interface hasbeen developed. Substantial progresshas been made in the development ofthe velocity calibration procedure asthe prototype instrument proceeds. Amethod of measuring the radius of afull-disk solar intensity image with anaccuracy and precision of a few partsin 103 while simultaneously determin-ing the MTF of the image has beendevised ( see box on page 7 ). Anartificial data set that includes steadyflows and several thousand p modesfor use in developing merging algo-rithms and for validation of the pipe-line is being assembled. A simplemerge by averaging remapped degrad-ed artificial images together with equalweights has been performed ( see boxon this page ). A comparison of thespectrum of the “perfect” data with themerged degraded data indicates thatthis baseline merging scheme does notsubstantially alter the measured fre-quency of the modes. The large

- 9 -33333333333333333333333333Access to the GONG On-line Storage Facility

The GONG Project has maintained a publicly readable on-line storagefacility since August, 1989. It includes one gigabyte of disk spaceinstalled on NOAO’s VMS/VAX. This will serve as GONG’s on-linestorage facility for the near future.

It may be accessed via INTERNET using FTP by an anonymous user.The procedure is as follows:

host: robur.tuc.noao.edu or 140.252.1.10login: anonftppassword: guest

followed by: cd gong.

To access the disk via NSI-DECNET use:noao::ga0:[ftp.gong] or5355::ga0:[ftp.gong];i.e., gazero

At present, the GONG project is not providing full function remotelogin. Anyone having questions about these procedures shouldcontact Jim Pintar.

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effects, that short frequent gaps haveon the power spectrum, have beendemonstrated and some methods offilling such gaps have been tested.Several papers discussing thesedevelopments will be published in theGONG ’92 proceedings and elsewhere.

The future plans of the DMAC de-velopment depend to a large extent onthe advice of the DUC. Several tasksneed to be addressed in the 18 months,or so, leading up to the deployment ofthe network. The DMAC must contin-ue to process prototype data, and willbe required to process the test datafrom the six field instruments as theyare completed. The integration of thepipeline must be both started and com-pleted by the time of network deploy-ment.

A new release of the GRASP soft-ware package will be available inmid-February 1993. Standard tests forvalidation of the pipeline must bedeveloped. The baseline pipelinemodules of merging, image restoration,peak finding, bad image rejection, anddetrending require further develop-ment. The newly-formed DUC, alongwith the advice of the GONG Com-munity, will be essential in helping theProject determine priorities.

Rob Cavallo who had been reducingdata for the GONG project left thegroup on June 18 to attend graduateschool at the University of Maryland.Rob had been working part-time forthe project while completing his un-dergraduate work at the University ofArizona, and we wish him well in hisnew venture.

In August, Jean Nowakowski joinedthe project accepting a position as adata reduction specialist. Jean trans-ferred to the GONG project from theKitt Peak staff where she had been alarge telescope operator and had ac-quired considerable experience withIRAF and with Sun workstations.

This Fall, part of the DMAC groupwill move from their present offices inthe NOAO building to a building locat-ed about 50 meters to the northeastthat several years ago housed the

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AURA corporate offices. This buildingwill be occupied by the people andequipment that make up the project’scomputer operation. In the near fu-ture, this building will be linked to theNOAO building with fiber optic cablesthat will support both FDDI and Ether-net communication. In addition, therewill be some minor renovation of theinterior of the AURA building. Sincethe computer hardware plans for theproject involve desk-top and desk-sideworkstations, major renovation (thatwould have been needed if the projecthad planned on installing super mini-computers) will not be needed. TheAURA building also has a room-sizedvault that will be used as the Exabytecartridge library.Frank Hill and Jim Pintar33333333333333333333333333333333

Project Management

The GONG Project has had a budgethistory not unlike many other Federal-ly funded programs. The proposal,prepared in 1985, called for funding ofabout $3M in three of the first five

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years, in order to finance the technicaldevelopment and major purchasesnecessary to construct and deploy thenetwork. The proposal was approvedand first funded in Fiscal Year (FY)1987. However, the vagaries of theFederal budget have caused the Projectto be funded at the levels varying from$1M to $2.3M, far below the optimumprofile. Nevertheless, excellent pro-gress has been made, although the pro-gram is necessarily taking more timeto complete than originally proposed.

Various adjustments in both thestrategy and tactics of the project planhave been made over time to deal withthe realities of the funding. In 1990,the Project presented a detailed revi-sion to a formal NSF review. Twofunding scenarios were presented, oneof which led to full network operationsin December 1993 and the other led tooperations in December 1994. Al-though the plans were favorably re-ceived, the actual and projected cumu-lative funding is below the “December1993 Plan” requirements by $1.4M.

Since 1990, the Project has pursueda plan intermediate to the two optionsabove. This calls for network

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Assuming level funding in FY 1993 and FY 1994, this plot shows the differencesbetween the actual/projected cumulative funding and that required to support theDecember 1993 and December 1994 plan options, respectively. Note that this funding is$400K short of even the December 1994 plan requirements.

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operations in June of 1994. The suc-cess of this plan depends on both thebudget and the resolution of the fewremaining technical issues.

On the funding side, the programhas been depending on annual budgetincreases from $2.3M in FY 92, to$2.55M and $2.68M in FY 93 and FY94, respectively. However, at thiswriting, the FY 93 budget increase isin serious question, as is the likelihoodof the FY 94 increase.

The cumulative funding to date hasbeen about the same as the “December1994 Plan”. This makes it tempting tosuggest that this would be a reasonable“new” target date for operations.However, if funding remains at thecurrent level in both 1993 and 1994there will be a shortfall of about$400K for even the December 1994date.

The uncertainties in the schedule areexacerbated by a number of technicalproblems that were very resistant tosolution. These have included cali-brating the images, finding an “ideal”camera (i.e. a technically suitablesquare-pixel camera), producing alow-noise stable laser system, andfinding a suitable modulator for the themagnetograph. The additional timespent addressing these problems hasdelayed the development of a numberof other desirable, though lower priori-ty, items. These include a 5-

oAngstrom

filter monitor, a scheme for compensa-ting for a timing bias in images takennear the horizon, and a higher level ofautomation for the turret to respond tovarious environmental conditions,beyond merely acquiring the Sun inthe morning, tracking it through theday, and shutting down in the evening.

For the past several months the Pro-ject has been engaged in a very de-tailed re-planning process directed atunderstanding the impacts of both thefunding and the development issues,and the alternative responses. The ob-jective has been to develop a programthat will provide the earliest possiblefielding of the complete network ofrobust, scientifically acceptable instru-

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ments.In one scenario, it was assumed that

the requested funding profile for 1993and 1994 remained intact. Thisscheme shows that the June 1994 datemight still be achievable if the follow-ing changes were made in the scope ofthe instrument:

Rectangular-Pixel CameraNo MagnetographNo LaserNo Timing-bias CorrectionNo 5

oA Filter Monitor

Limited AutomationThis approach sidesteps the develop-

ment delay by canceling further workon features or systems that remainunfinished at this point. Unfortunate-ly, this appears to be a plan withoutmuch slack. Any further perturbationswould likely delay the network com-pletion date beyond June. Obviouslysuch descopes will have an impact onthe scientific capabilities of the instru-ment and these impacts were discussedvigorously at various scientific team

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meetings in Boulder. The Project re-ceived many useful thoughts aboutthese issues and they were consideredcarefully before the descope decisionswere actually made.

Other actions to expedite networkdeployment are also being considered.Among these are reducing the time de-voted to testing, burning in, and certi-fying the field instruments before de-ployment. In the current plan, thereare several levels of quality assurance,including tests at the board, mechan-ism, subsystem, system, and fully-integrated levels. It is possible to cur-tail or skip some of these steps. Simi-larly, the plan calls for two months ofdaily operations for each instrument inTucson before it is dismantled andshipped to its field site. This periodcould be shortened.

This plan is devoted to the notionthat, in the end, the fielded system willbe much more reliable, field outagesthat might compromise the whole net-work will be shorter, and the network

- 11 -33333333333333333333333333will be far less expensive to maintain,if we pay considerable attention tomaking sure that the start-up problemshave been cured and each systemworks correctly before it is deployed.It is the Instrument Team’s positionthat any shortcuts taken in the quality-assurance area be very carefully con-sidered, lest they have serious impactson the scientific efficacy of the system.

In some sense, the issue may bemoot. If the funding profile is notmaintained, then a deployment delay isinevitable in any case. Since thislooms as a very real possibility, theoption of taking the extra time andlimiting the descopes is also a reason-able prospect. This would strengthenthe capabilities of the instrument at theexpense of time that really could notbe recovered anyway. It should bepointed out that since a six-month de-lay, back to the December 1994 date,would provide access to three monthsof FY 95 funds (the Project is fundedannually from October to September),this could be used to cover at leastsome of the funds shortfall.

The real choices will be clear in thenext several weeks when the Federalbudget comes into sharper focus. Inthe meantime, the Project is workingvigorously to expedite the conclusionof the production, and the deploymentof the field stations. The finalconfiguration of the instrument hasbeen frozen, included some, but notall, of the potential descopes men-tioned earlier (see the instrument re-port for details). Network deploymentstrategies have been devised for boththe June 1994 and December 1994 fullnetwork operations dates ( see below ).

We believe that the average deploy-ment time for a station will be aboutone month. There will be twodifferent teams each doing the “rough”installation of three stations, and oneteam that will do the final alignmentand certification for operation.

The teams will alternate in the fieldso that the unavailability of any oneperson will not obstruct an installation;that skill can be borrowed from the

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other team. Similarly, if a particularinstallation runs into trouble, as muchas two months can be devoted to itwithout delaying the overall schedule.

The order of the first two deploy-ments is driven by logistics, training,and merging considerations. The Cali-fornia site is the physically closest siteto Tucson and it will represent a first“baby step” deployment effort. Supplyand communications lines are shortesthere. It will represent a training exer-cise for both teams under fairly con-trolled circumstances.

Moreover, the prototype instrumentwill be in daily operation in Tucson.As soon as the Big Bear instrumentcomes up, the DMAC team will haveits first access to real data to test andpractice merging. The Hawaiian ins-tallation represents the next logical ex-tension of these same philosophies.Here the testing of three-site mergingwill become practical. The balance ofthe deployment order is based on ex-pectations of seasons and weather:

January-June DeploymentJan California Winter AFeb Hawaii Winter BMar India Spring AApr Chile Fall CMay Spain Summer BJun Australia Winter C

July-December DeploymentJul California Summer AAug Hawaii Summer BSep Spain Fall BOct Australia Spring CNov India Fall ADec Chile Summer C

The A, B, and C identify conjugatelongitude pairs. One can begin to ap-proximate a network when at least oneset of conjugate pairs is operational.In the two options above, this happensafter the deployment of the third sta-tion in each case.

The decisions on schedule, scope,and budget will be made by the Pro-ject in consultation with the ScientificAdvisory Committee and the ScienceTeam leaders during the Fall, as hardfiscal information becomes available.Jim Kennedy

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Data Managementand Analysis Review

33333333333333333333333333333333Report of the

DMAC Review Panel

The GONG DMAC Review panel,comprising Ron Allen, Tim Brown,Dick Grubb, Gareth Hunt, Tuck Steb-bins (chair) and Roger Ulrich, met atthe National Solar Observatory in Tuc-son May 25 and 26, 1992. The panelmembers had previously received areference document, entitled “GONG’sDMAC: System Development PlanReview” (GONG Technical Report#92-1). The panel heard presentationsfrom GONG Project members aboutDMAC requirements, development andplans. A computer system solutionwas described and costed. The panel’sreport consists of a response to each ofthe three parts of its charge and a setof recommendations.

By their very nature, reviews of thissort concentrate on tasks not yet com-pleted and on suggesting changes.However, we wish to acknowledge atthe outset the accomplishments andprogress of the GONG Data Team.The task of building the DMAC iscloser to the end than to the beginning.The Project has extensive experiencewith Exabytes, the medium underlyingthe whole enterprise. Prototype soft-ware for most of the processing is inhand. Data from breadboard and pro-totype have been reduced. Severalnovel algorithms have been developedalong the way: calibration of the in-strumental idiosyncrasies; a new meth-od of radius and MTF determination;the spherical harmonic transform is nolonger the overwhelming computation-al burden it was once thought to be;the merging of synthetic data has beendemonstrated; and a unique peak-finding algorithm has been developed.The design and construction of theDSDS, the final component of theDMAC, has begun. A competent andprofessional staff has been assembled.

- 12 -33333333333333333333333333The problem of GONG data process-ing and storage has been sized, and acomprehensive plan is in hand. Thebaseline system appears to be imple-mentable within the budget. We com-mend the Data Team for theseachievements.

Response to the Charge“Will the planned system provide an

optimum solution for achieving theproject’s objectives in a cost effectivemanner?”

The panel endorses a distributedcomputing system similar to Plan Adescribed in the document. Such asystem has the great strength of exten-sibility by increments which have theperformance and price available at thetime of purchase. This, together withthe interoperability of software onUNIX systems, gives the Project theflexibility to respond to changes in themarketplace and avail themselves ofthe latest technical advances. How-ever, we suggest a couple of modifica-tions: the DMAC should have onemachine function as a server of com-mon software to all others to reducemanagement costs as a benefit of thenetwork interconnections (see theRecommendations Concerning Soft-ware Engineering below); and a singlevendor should be chosen, if at all pos-sible. If vendor change is dictatedduring the lifetime of the project, theProject will have to sustain the costsassociated with migrating software toanother architecture at that time, butneed not incur that cost before, norbear the burden of supporting multipleplatforms, possibly unnecessarily.

The Project’s objectives, as stated insection 2 of the reference document,are likely to be met by a distributedsystem, but whether such a system willsatisfy the expectations of the sciencecommunity is not clear, since, as de-monstrated by discussions during thepanel meetings, those expectations arenot well known. See Recommenda-tions Concerning Community Involve-ment below.

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“Will the planned system accommo-date the development of the currentlyundefined components of the system?”

At the level of the baseline DMAC,some of the undefined components (cf.section 3 of the reference document)are in fact defined. The instrumentcalibration is, or has been, successful.It isn’t yet known whether recent in-strument changes have rendered it un-successful. Image restoration is notpart of the baseline PIPE, but iscurrently considered an enhancement.The baseline PIPE includes a multi-site merge that appears to work.

The panel notes with satisfaction thehigh priority given to bringing thecomputational requirements of themode frequency identification algo-rithm within the reach of affordablecomputers. The expandability of adistributed architecture assures thatprocessing power can be added to theextent affordable. This component isrendered “undefined” not for want ofan algorithm, but rather because of aconflict between cost and budget.What is needed here is an alternate al-gorithm demanding less computationalpower — a situation not likely to beincompatible with the recommendedplan.

The panel regards automatic bad im-age identification and rejection asnecessary to the success of the DMAC.This algorithm should be part of thebaseline system, and its developmentshould be accorded appropriate resour-ces. We note the preliminary reportsof some early progress. We suggestthat the data acquisition system at theobserving sites might aid in theidentification of bad images.

“Will the planned system provide aflexible basis for the evolution of com-puter systems, enhancement of datareduction algorithms, and improve-ments to the observing instrumentthroughout the lifetime of the project?”

A distributed system with affordablecomputers, running UNIX, does pro-vide a flexible basis for expanding theDMAC, or migrating the system toanother hardware platform if that

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should be desirable. [See the Recom-mendations Concerning the DataStorage and Distribution System for asuggestion concerning evolution of thesystem from operator mounted tapes toa robotic carousel.] Likewise, the dis-tributed system admits expansion foralgorithm improvements. Note, how-ever, that the prototype nature of theDMAC demands a scheme for manag-ing the evolution of the software. Ourrecommendations are found below inthe context of suggestions for softwareengineering. We also make recom-mendations about augmenting thefunctionality of the DMAC below inthe context of community interaction.

We believe that the project wouldbenefit from the development of a pri-oritized list of possible enhancementsto the DMAC baseline, in which priori-ties reflect both desirability and cost(see Recommendations ConcerningCommunity Involvement below).

We don’t know enough about possi-ble improvements of the observing in-strument to assess whether the plannedarchitecture structurally impedes adap-tation of the DMAC.

Recommendations ConcerningCommunity Involvement

The committee notes that the DMACteam does not appear to have amechanism for feedback from theGONG user community which issufficiently frequent to be of effectiveuse in guiding the development of theDMAC project. The lack of frequentand effective feedback means that aheavy burden of responsibility is puton the DMAC group to make cost andschedule decisions which accuratelyreflect the priorities of the helioseis-mology community, and converselyexposes the development group to bearthe full brunt of mistakes in that pro-cess. On the other side, the GONGuser community is not currently inti-mately involved in the necessary cost-schedule tradeoffs occurring in thepresent DMAC design process, andtherefore may well find that the result-ing product is, in the end, not

- 13 -33333333333333333333333333Yet Another Newsletter

The δ Scuti community has a newsletter edited by Michel Breger( breger@avia.una.ac.at ). It contains abstracts of papers and othernewsworthy items that many of our readers might well be interested in.

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acceptable to them. The result is thatboth sides can lose. It is imperative tobuild a line of communication whichensures that the responsibility isshared. We view this as the most im-portant advice we can give to theDMAC project at this time.

The committee therefore recom-mends that the DMAC leadership ac-tively explore ways to involve thesolar physics community in a moredirect and frequent manner in theDMAC development process. As apossibility, we suggest the creation ofa DMAC Users Committee consistingof perhaps no more than 4-6 personswho would meet with the DMACdevelopment group in Tucson forperhaps a day every 3-4 months inorder to review parts of the system indetail through e.g. hearing stand-uppresentations and evaluating hands- ondemos of the software. This UsersCommittee would be a subcommitteeof the GONG Data Analysis andReduction Team, would report back tothat team on perhaps a yearly basis,and would have a mandate from theteam to act on their behalf in matterspertaining to the development ofDMAC. The project needs, and theUsers Committee could provide, com-munity input on the priority of thevarious science data products, thedefinition of the user interface, thepriority of DMAC augmentations, andthe nature and level of visitor supportin Tucson. On the other side, thisUsers Committee can be seen by theDMAC development group as thesounding board from whom they mayseek approval and support for the inev-itable trade-offs which must be madeduring the development process, andas the body which shares the responsi-bility for those decisions.

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Recommendations ConcerningSoftware Engineering

In order to track the changes duringthe development of the project, werecommend that you adopt aConfiguration Management system tomaintain the code. We note that theDMAC code modules will not, in thenormal process of events, be modifiedby more than one person. Neverthe-less, the historical tracking of the soft-ware system may be extremely impor-tant later in the project. The configu-ration management should included archiving of any software change

made to the production systemd inclusion of software release version

numbers in the historyd information associated with the pro-

cessed dataIn order to facilitate future maintai-

nability and to ease the reassignmentof software personnel, we recommendthat the project adopt a set of softwarestandards. We note that coding stan-dards exist for modules written in theGRASP system. We recommend thatsimilar coding standards also be ap-plied to all other software. These in-cluded selection of a programming

languaged selection of a common UNIX shelld coding standards for the selected

language(s)d code documentation standard and

documentation extractor(s)d peer review of code submitted to the

systemWe suggest effort be devoted to iso-

late implementation specific UNIXoperating system and shell dependentfunctions into specific libraries. Thiswill ease the conversion effort requiredto move the code from one UNIXhardware platform to another, shouldthis become necessary.

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We strongly recommend that youuse a configuration of workstations tominimize the personnel cost of systemmanagement. Where possible the op-erating system, system utilities, andother common general purpose soft-ware should be centrally installed andmaintained. Although we recognizedthat several different architectures maybe necessary, we recommended thatyou limit the number of different ar-chitectures where possible. Systemmanagement tools vary considerablybetween different architectures.

Recommendations Concerningthe Data Storage andDistribution System

The committee recommends thatseveral steps be taken to minimize therisk of human error in handling theExabyte tapes, both to prevent loss ofdata due to mistakes in mounting tapesand to prevent actual physical damageor loss. Specifically:

Physical labels for both the tape andits container should contain the Vol-ume ID number in bar coded form.The use of bar code readers at the li-brary checkout then guarantees correctentry of transactions into the catalogdata base and facilitates searches for atape which has been physically mis-placed in the storage system.

When the tape is originally certifiedand issued an ID, this number shouldbe recorded in an ID block at the be-ginning of the tape. If each stage ofthe processing then registers tape usewith the catalog, this will permit au-tomatic tracking of the tapes throughthe pipeline and independent veri-fication that the correct tape has beenmounted at each stage.

To avoid original data tapes becom-ing misplaced or damaged it is sugges-ted that their movement be restrictedto as small an area and as few loca-tions as possible. One possibility isthat all data be transferred electronical-ly from a single server with multipleExabyte drives adjacent to the library.This would essentially emulate arobotic carousel using a human tape

- 14 -33333333333333333333333333GONG Papers Submitted for Publication

E. Anderson, Gap Filling the GONG Data SetR. Bogart, F. Hill, et al., Artificial Data for Testing Helioseismology

AlgorithmsJ. Harvey, F. Hill, J. Kennedy, and J. Leibacher: “GONG Project

Update”S. Korzennik and S. Sabbey: Measurement of the Phase Relation

Between Velocity and Intensity Fluctuations Induced by Solar P-Modes from GONG Breadboard Data

D. Hathaway: Doppler Measurement of the Solar MeridionalCirculation

J. Pintar and M. Trueblood: GONG’s DMAC: Update and Current PlansC. Toner and S. Jefferies, Accurate Measurement of the Geometry for

a Full-Disk Solar Image and Estimation of the Observational PointSpread Function

W. Williams, F. Hill et al., Tests of Simple GONG p-mode MergingAlgorithm

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operator. This would facilitate laterconversion to an automatic system,and we recommend that the projectkeep this possibility in view as afford-able robotic systems are likely to be-come available in the future. Anotheralternative, given that the pipeline pro-cessing will be remote from the mainlibrary, would be to set up a separatestaging library for the tapes in use bythe pipeline adjacent to the processingarea and provide for local access to thecatalog data base. The necessarytransfers from the staging library to themain library could then be made moreinfrequently in bulk and under moreformal control than would be the casefor frequent individual tape move-ments.

Recommendations ConcerningPersonnel

We are concerned that the plannedpersonnel level is not adequate to dealwith contingencies. The plan is con-figured primarily to manage the ongo-ing reduction of the incoming datafrom the network. The operationalpersonnel seems about right to keep upwith the incoming data. However, wefeel that there will almost certainly besubstantial sequences which will needto be reprocessed to utilize improve-ments in data reduction algorithms.

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Experience with other large astronomi-cal databases from projects like GONGindicates that the initial reductionmethods are invariably not the bestthat can be done. In this case the fullutilization of the database will requirea complete re-analysis of the datawhich was reduced prior to the im-proved algorithm. Re-reduction ofsubstantial portions of the databasecould also be required if, for example,difficulties in the data merging — themost novel aspect of the GONG pro-ject — were discovered after sometime period. Because of the probabilityof such contingencies, we feel it islikely that the personnel for the opera-tions has been underestimated.

We recommend that likely con-tingencies be analyzed to determinetheir impact on DMAC operations,especially on staffing. Past experiencewith the processing of breadboard andprototype instrument data might illus-trate where on the data processinglearning curve the Project is and whatpersonnel resources might be calledfor.

The personnel assigned to thedevelopment of new algorithms dropsfrom nine to four after the start of net-work operations. We regard continueddevelopment as an essential ingredientof a scientific study where many tasks

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are poorly defined prior to the opera-tion of the experiment. The prototypenature of the DMAC and the scientificimportance of the augmentations al-ready being considered (e.g. peak-finding on the full power spectrum,low frequencies, steady flows) sug-gests that higher development staffingbe considered. This shortage would beexacerbated if the development person-nel must also support the above men-tioned contingencies.

While students will be adequate forsome routine production work, thepressures associated with normalcourse activity may introduce undesir-able schedule irregularities in theiravailability. Long term operators willalso develop experience with apprais-ing incoming data and intermediatedata products which will likely be cru-cial to the operation of the pipeline. Acore of professional operators may bemore appropriate for the pipeline re-ductions with the student operatorsused in a flexible backup role. Thiswill allow participation by students inthe GONG project without necessarilymaking them responsible for perform-ing time-critical tasks. We recom-mend that a substantial fraction of theDMAC operators be professionaloperators as opposed to student opera-tors.

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to theRecommendations from the

DMAC Review Panel

The plan for the GONG’s DMACwas reviewed by a panel of outside ex-perts on May 25 and 26, 1992. Theproject was gratified by the contribu-tions of the panel; in particular, by thescope and depth of their inquiry, andwe are pleased that the panel felt thatthe plan will satisfy the requirementsand objectives of the project. In addi-tion, the panel has offered several use-ful suggestions that will significantlyimprove the project. Below is a list ofthe recommendations (in italics) ex-

- 15 -33333333333333333333333333Data Requests

The following GONG members have received data:

David Hathaway — Meridional FlowsSylvain Korzennik and Bob Noyes — Velocity-Intensity Phase RelationsRoger Ulrich and John Beck — Signatures of Magnetic Active Regions

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tracted from the Panel’s written reportfollowed by the project’s response toeach item.

A single vendor should be chosen, if atall possible: The project agrees that ahomogeneous hardware environmentoffers many advantages and has begunthe process of selecting a single ven-dor.

Develop a mode frequency identi-fication algorithm within the reach ofaffordable computers: A mode fre-quency identification algorithm capa-ble of operating at cadence on afford-able equipment is a requirement forthe baseline system. A high level ofpriority has been attached to this ob-jective.

Include bad image identification andrejection in the baseline system.: Theproject agrees with the importance ofthis objective and will automate theidentification and rejection of bad im-ages to the degree possible.

Actively explore ways to involve thecommunity in a more direct and fre-quent manner in the DMAC develop-ment process: There are many projectissues that can only be answeredthrough dialogue with the GONG com-munity. A formal users’ committeewill be a very effective means for thethe project to obtain concrete inputfrom the scientific community regard-ing these issues. The project will pro-mote and facilitate the creation of apermanent users’ committee.

Employ a configuration managementsystem including the archiving of oldversions, version numbers in the

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process histories of the images, andprocessing parameters in the processhistories of the images: This recom-mendation will be implemented. Be-fore 1992, the project had assembledand released a version of the project’ssoftware packages inside IRAF. Theproject will return to this practice.The desirable features of these“released versions” are that the processof assembling the release controls theproliferation of development code, theobsolete releases are routinely retained,and the project has a well-documentedprocedure for the assembly of therelease. In the near future, the projectwill take several steps to record timestamps and processing parametersmore systematically. For the non-IRAF part of the system, SCCS is be-ing evaluated as a mechanism to trackand control source code and compila-tions.

Establish consistent software stan-dards: select a programming languageand a UNIX shell, isolate OS and shelldependencies, establish coding stan-dards, provide code documentation ex-traction, and peer review of code sub-mitted to the system: Currently, threecompiled languages: FORTRAN, C,and SPP (IRAF’s compiled language)are used for the image reduction appli-cations. This is consistent with therecommendations of the Pre-AlphaDesign Review (1990) and with pastexpressions of opinion from the com-munity. The compiled language forthe field tape reader and DSDS is C.In the near future, the project willselect a UNIX shell. We agree that itis appropriate to begin introducingcommonly accepted software qualitypractices. In particular, the project

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will begin using peer reviews to helpensure the quality and consistency ofthe code and related products that theDMAC produces.

Centralize workstation administration:At the start of network data reduction,the project will have two people whowill share responsibility for system ad-ministrative tasks (assuming that thetransition to a homogeneous environ-ment will be completed).

Use bar-coded volume serial numbersand a bar-code reader and put amachine readable, tape label on thecartridge as part of the cartridge con-ditioning and initialization process:The project is actively investigatingboth of these suggestions. It is likelythat both will be implemented. Abar-code reader will be purchased andevaluated in the near future.

Minimize the movement of originaldata cartridges throughout the physi-cal space occupied by the DMAC: Theproject has several options that can bepursued to enhance the physical securi-ty of the cartridges in the data storagefacility. These range from changes tothe computer system plan to methodsof restricting physical access to the fa-cility. The project agrees that im-proved physical security is needed andis currently evaluating the availableoptions to develop a solution that willbe effective in terms of cost, security,and performance.

May need more processing personnelto deal with the possible need forreprocessing and more personnel toprovide for ongoing development: Theimplementation of this recommenda-tion will depend on the level of avail-able funds for salaries and computerequipment and will likely require thatthe project request additional fundingfrom the NSF. The project will notpursue an increase in the DMAC’sbudget now; however, this possibilitywill be factored into out-year budgets.

- 16 -33333333333333333333333333Use professional operators rather thanstudent operators: We agree with thePanel’s recommendation that the ex-tensive use of student operators wouldlikely be counter-productive. Savingsin salary would be lost to lower pro-duction associated with frequent train-ing of new employees and constantreassignment of tasks to accommodatestudents’ academic schedules.

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Team ReportsThe six GONG teams met during the“GONG ’92” meeting, and here aretheir reports.

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Data Reduction and Analysis

The following issues were discussedin the Data Reduction and AnalysisTeam meeting: the baseline pipeline,merging, the database and data catalog,the Data Management and AnalysisCenter (DMAC) Review Panel and theDMAC Users Committee (a.k.a. DUC).Tuck Stebbins opened the team meet-ing with a call for input from the com-munity to DUC.

A discussion of the baseline pipelinearose spontaneously following theGONG Project Update session as a re-sult of Frank Hill’s report of Projectactivity in the previous year and thesolicitation for DUC. One outgrowthof the discussion was a concern withpeak finding using m-smoothed spec-tra. [ This choice in the baseline soft-ware reflects the fact that m-indepen-dent peak finding requires more com-putational capacity than the Projectcan afford, and maintain cadence.] APeak-Finding Subteam was spontane-ously formed by Ed Anderson, JørgenChristensen-Dalsgaard, Sylvain Kor-zennik, Phil Stark, and Jesper Schou toinvestigate alternate algorithms whichpreserve m information and are compa-tible with processing resources.

The Project has successfully mergedartificial data. Dave Hathaway genera-ted solar velocity images with a

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variety of solar velocity fields. TimBrown contributed a code to degradethose images into network images withrealistic noise models. Winifred Willi-ams, Cliff Toner and Frank Hill thenextended Tim’s software and success-fully merged the data with a simpleaveraging algorithm. These resultswere reported in poster paper #7-3.Tim has experimented with othermerging algorithms on artificial as-teroseismology data, reported in poster#7-5. He concludes that simple data-averaging is better than other methods,except a good data window, which isbest.

Mark Trueblood gave a presentationon the user interface and structure ofGONG’s Data Storage and DistributionSystem (DSDS). He described howqueries will be formulated and how re-quests for data will be presented.There followed a discussion of thepros and cons of making engineeringand data quality information availableto the users. In the baseline plan, theProject does not have this informationin the user-accessible database. VickiJohnson showed a mock-up of the userinterface for the SOI database. Thegraphical user interface includes infor-mation about the spacecraft, observingcampaigns, and operations, and it sup-ports graphical presentation of somedata parameters and data requests.

In May, a DMAC Review Panel wasasked to review the progress of theGONG data reduction effort and futureplan. Frank Hill summarized the re-view process in his presentation as partof the GONG Status Report. A back-ground document, a Panel Report anda Project Response have been com-piled, and are (or soon will be) avail-able for distribution to interested mem-ber of the GONG community. ContactFrank Hill at NSO for a copy.

One outgrowth of the DMAC Re-view Panel was a Users Committee, tomeet three or four times per year inTucson. The purpose of the commit-tee was to act as a conduit between theDMAC development group and theGONG community. The Committee

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was intended to advise on cost/schedule decisions in a manner whichreflects community priorities and toensure that the resulting product is ac-ceptable to the community. Thecurrent membership of the group isTuck Stebbins (Chair), Tim Brown,Jørgen Christensen-Dalsgaard, ToddHoeksema and Roger Ulrich. Mem-bers will serve either two or three yearterms to provide for rotation and con-tinuity. Members of the greater GONGcommunity are encouraged to voicetheir opinions about the DMAC toDUC members. Tuck Stebbins33333333333333333333333333333333

Models1. Introduction.

There has been little organizedModel Team activity since the previ-ous GONG meeting. Hence, the statusof the models comparison project isunchanged and as described in GONGNewsletter No. 17: very decent agree-ment has been found between theresults of four independent calculationsof models with simplified physics, in-dicating that there are no significantnumerical problems in these calcula-tions. These results should ideally becollected in a publication wrapping upthis part of the project, and defining asimple reference with which other in-dependent calculations could be com-pared; that this has not happened issolely due to the inefficiency of theteam chairman responsible for thiscomparison project. In addition, therehave been comparisons between calcu-lations using realistic physics, againindicating overall good agreement.

Much activity has been concernedwith computing solar models and os-cillation frequencies with the recentOPAL opacities from Livermore ( e.g.,Rogers & Iglesias 1992 ). A review ofsome of these results was given byMike Thompson at the GONG meet-ing. Dziembowski, Pamyatnykh &Sienkiewicz (1992) found that using

- 17 -33333333333333333333333333The Institute for Advanced Studies at the Hebrew University

announcesTHE TENTH JERUSALEM WINTER SCHOOL IN THEORETICAL PHYSICS

onNeutrino Astrophysics

29 December 1992 - 7 January 1993Co-Directors: JOHN N. BAHCALL & STEVEN WEINBERGCoordinator: TSVI PIRANLecturers: JOHN N. BAHCALL (IAS Princeton)

PETER ROSEN (UT Arlington)MICHAEL S. TURNER (FNAL and Chicago)LUIS IBANEZ (CERN)

The School will discuss theoretical aspects of neutrino astrophysics as related to recent experimentalresults. There will be lectures on the fundamentals of solar model theories, including nuclear reactions,radiative opacities, equations of state, and various plasma effects. Another series of lectures will present thebasic elements of MSW theory and show its relation to solar neutrino experiments, to the theory of supernovaexplosions, and to atmospheric neutrinos. These lectures will also place MSW theory, and its relatedextensions, in the context of other recent developments in weak interaction theory. The role of neutrinos andother possible weakly interacting particles will be described in conventional and unconventional cosmologicaltheories; the relation of these ideas to recent cosmological observations will be stressed. The consequencesof the possible demonstration of a small neutrino mass of the order suggested by MSW theory will be outlinedin the context of a general discussion of physics beyond the standard electroweak model.

Additional, special lectures will be given regarding the status and plans of individual neutrino experiments,with some discussion of the possibilities of new terrestrial tests (using reactors and accelerators). There willalso be special lectures on astronomical sources of high-energy neutrinos and on the ratio of electron-neutrinos to muon neutrinos observed in atmospheric neutrino experiments.APPLICATIONS: The School is intended for qualified students at the graduate or post-doctoral level from allcountries. Applications should include a short curriculum vitae, a description of research interests and a letterof recommendation.DEADLINE FOR APPLICATION: The number of participants is limited.FEE: Registration fee, lodging + half board for the duration of the school is $500 ($150 registration fee only).A limited number of grants will be available. Applicants who wish to request financial support should submit anexplanation of financial needs.ADDRESS FOR APPLICATIONS: Jerusalem Winter School of Physics,

Institute for Advanced Studies,The Hebrew University of Jerusalem,91904 ISRAEL.Bitnet: ADVANC@HUJIVMS.Fax: 972-2-523429.

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OPAL opacities resulted in a strikingimprovement in the agreement be-tween the model sound speed and thesound speed resulting from invertingsolar data. Subsequent improvementsin the OPAL opacities, particularly theadoption of a revised iron abundance,has increased the discrepancy some-what, however. A second area of

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substantial activity has been investiga-tion of the diagnostic potential of thephase function α(ω) arising in the Du-vall law for the asymptotic behaviourof acoustic-mode frequencies. This isparticularly relevant for investigationsof the equation of state in the hydro-gen and helium ionizations zones, andfor determinations of the envelope

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helium abundance ( see Christensen-Dalsgaard & Perez Hernandez 1992;Vorontsov, Baturin & Pamyatnykh1992 ). A detailed investigation of theability of determining the envelopehelium abundance from helioseismolo-gy, given the uncertainty in the equa-tion of state, was carried out by Koso-vichev et al. (1992). Although the

- 18 -33333333333333333333333333uncertainties are substantial, the resultsgenerally indicate an envelope heliumabundance Ye by mass of 0.23 - 0.25,somewhat lower than the value of theinitial helium abundance Yo of about0.27 required to calibrate the modelsto have the correct present luminosity.

It has come to be realized that diffu-sion and settling may play a significantrole in the Sun. Proffitt & Michaud(1991) made a careful comparison ofdifferent formulations used to treatthese processes. They concluded thatas a result of settling the present valueof Ye would be reduced by 0.03, rela-tive to the initial value Yo. Includingweak turbulent mixing beneath theconvection zone would reduce this de-crease somewhat; however, if the mix-ing is constrained by restricting lithi-um and beryllium destruction to beconsistent with the current observedsurface abundances, there remains adecrease of Ye of about 0.02. Verysimilar results for the basic diffusion( neglecting possible turbulence ) wereobtained by Bahcall & Pinsonneault(1992); they also pointed out that as aresult of diffusion the depth of theconvection zone of the model is in-creased, to match quite closely thevalue determined from helioseismol-ogy. It should also be noted thatdifference between the present Ye andthe initial Yo may account for thediscrepancy between the helioseismi-cally inferred helium abundance andthe value required to calibrate themodels. Very recently, Christensen-Dalsgaard, Proffitt & Thompson ( inpreparation ) have found that inclusionof diffusion, using also the most recentOPAL opacity tables, results in goodagreement between the sound speed inthe model and the solar sound speedinferred from inversion of observedfrequencies.

During the GONG meeting a specialjoint discussion was held of the Modeland Inversion Teams. Here themodel-related discussion centered onthe provision of reference solar modelsfor the GONG project. One suchmodel, computed by R. K. Ulrich, has

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been available for some time. JC-Doffered to make available a recentlycomputed model, using up-to-dateOPAL opacities and a thermodynami-cally consistent implementation of theCoulomb correction to the equation ofstate. This model was computed with1201 mesh points, and hence shouldbe numerically quite accurate; it hasthe further advantage that the underly-ing evolution code has been testedthrough the comparison of modelswith simple physics. The modelwould be provided together with a pro-gram for computing adiabatic oscilla-tion frequencies and eigenfunctions, toallow setting up the kernels requiredfor, e.g., rotational inversion. It ishoped that this package will be readyby the end of the year.

There was a very interesting discus-sion about the most suitable form forsuch a model, and the possible uses ofit. There is a strong advantage to havea single accepted reference model onwhich, e.g., inversions are based; inthis way a unique meaning can be as-signed to resulting differences betweenthe Sun and the model. It may be lessimportant that the model is “right”, inthe sense of providing the best possi-ble fit to the data, although it should ofcourse be based on the best possiblecurrent physics. Indeed, given the un-certainty in the treatment of the super-ficial layers of the Sun, perfect agree-ment between the computed adiabaticoscillation frequencies and observedfrequencies would almost have to bespurious, resulting from a cancellationof errors. ( It should be recalled thatsuch uncertainties give rise to an errorin the computed frequencies which,when properly scaled, is a function offrequency alone; e.g., Christensen-Dalsgaard & Berthomieu 1991 ). Thismight argue for using a model withvery good and well-defined physics,but with no attempt to adjust parame-ters to improve the fit to the observa-tions. On the other hand, for applica-tion of the model to inversions, this ar-gument may have to be reconsidered.Insofar as the interior of the model is

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concerned, it seems plausible thatcurrent realistic models are sufficientlyclose to the Sun that linearized struc-ture inversion would be adequate, re-gardless of the details of the model.However, the uncertainties at the stel-lar surface introduce phase shifts in theeigenfunctions, and hence in the ker-nels, which could lead to systematicerrors in the inversions. This clearlyapplies also to inversion for rotation,or other properties of the solar interiornot directly related to the sphericallysymmetric component of structure. Toavoid problems of this nature it mightbe preferable to adjust the model suchas to minimize the effects of the sur-face uncertainties. This can in fact beachieved through artificial changes inthe surface opacity. It might then betempting also to “improve” the refer-ence model in the interior, throughfurther opacity modifications, in orderto reduce further the differencesbetween observations and theory. Thedrawback of such a procedure is evi-dently that the model becomes moredifficult to define precisely and toreproduce.

These issues were not resolved atthe meeting, and hence further discus-sion is needed. One problem that re-quires immediate attention is the effectof model uncertainties on the resultsof, for example, inversion for rotation.Christensen-Dalsgaard and Gough(1984) made experiments of that na-ture, by setting up artificial data basedon one solar model and inverting themwith kernels computed for a ratherdifferent solar model. The conclusionat that time was that the uncertainty inthe model had little effect on inver-sions based on five-minute modes; butthe question probably has to be recon-sidered, given the improved precisionof the observations and the resultingchange in standards. It might also benoted that Christensen-Dalsgaard,Gough & Thompson (1991) and Koso-vichev et al. (1992) found certain as-pects of the structure inversion to berather insensitive to the choice ofreference model, over a substantial

- 19 -33333333333333333333333333range of such models. Again, there isa need for more systematic investiga-tions, however.

My current inclination would be toprovide two reference models: onewith no artificial modifications, andone where the atmospheric opacity hasbeen increased artificially to eliminateas far as possible the frequency-dependent part of the differencebetween observed and computed fre-quencies. Diffusion would not be tak-en into account: although undoubtedlysignificant, it is still a somewhat“non-standard” feature, and further-more there is considerable uncertaintyabout the detailed description of tur-bulent mixing beneath the convectionzone. Speedy comments on thissuggestion would be much appreciat-ed. Jo/ rgen Christensen-DalsgaardReferences

Bahcall, J. N. & Pinsonneault, M. H.,1992. “Helium diffusion in the Sun”.Astrophys. J., 395, L119 - L122.

Christensen-Dalsgaard, J. & Berthomieu,G., 1991. “Theory of solar oscillations”.In Solar Interior and Atmosphere, p. 401- 478, eds Cox, A. N., Livingston, W. C.& Matthews, M., Space Science Series,University of Arizona Press.

Christensen-Dalsgaard, J. & Gough, D. O.,1984. “Rotational inversion from globalsolar oscillations”. Solar seismologyfrom space, p. 79 - 93, eds Ulrich, R.K., Harvey, J., Rhodes, E. J. & Toomre,J., NASA, JPL Publ. 84-84.

Christensen-Dalsgaard, J. & Perez Her-nandez, F., 1992. “Phase-functiondifferences for stellar acoustic oscilla-tions — I. Theory”. Mon. Not. R. Astr.Soc., 257, 62 - 88.

Christensen-Dalsgaard, J., Gough, D. O. &Thompson, M. J., 1991. “The depth ofthe solar convection zone”. Astrophys.J., 378, 413 - 437.

Dziembowski, W. A., Pamyatnykh, A. A.& Sienkiewicz, R., 1992. “Seismo-logical tests of standard solar modelscalculated with new opacities”. ActaAstron., 42, 5 - 15.

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Kosovichev, A. G., Christensen-Dalsgaard,J., Dappen, W., Dziembowski, W. A.,Gough, D. O. & Thompson, M. J., 1992.“Sources of uncertainty in direct seis-mological measurements of the solarhelium abundance”. Mon. Not. R. Astr.Soc., in the press.

Proffitt, C. R. & Michaud, G., 1991.“Gravitational settling in solar models”.Astrophys. J., 380, 238 - 250.

Rogers, F. J. & Iglesias, C. A., 1992.“Radiative atomic Rosseland mean opa-city tables”. Astrophys. J. Suppl., 79,507 - 568.

Vorontsov, S. V., Baturin, V. A. &Pamyatnykh, A. A., 1992. “Seismologyof the solar envelope: towards the cali-bration of the equation of state”. Mon.Not. R. Astr. Soc., 257, 32 - 46.

33333333333333333333333333333333Inversions

Approximately 30 enthusiasts at-tended the meeting of the InversionTeam, which was chaired by JuriToomre, one of the team co-leaders.Douglas Gough, the other co-leader,was unfortunately unable to attend themeeting.

During the past year, some efforthas been directed towards the produc-tion of standardized user-friendlyinversion software packages. Thesepackages will allow new workers toquickly gain the ability to inverthelioseismic data. Jørgen Christen-sen-Dalsgaard, Jesper Schou, and MikeThompson are developing an IDL/X-windows-based package that wasavailable during the GONG meetingfor hands-on demonstrations. Thispackage performs a smoothness-constrained least squares inversion. Itis expected that this software will bepublicly available when developmentis complete, and that it will eventuallybe integrated into the SOI SSC.

John Brown brought the existenceof a journal exclusively devoted to in-verse theory to the attention of theTeam. The journal, titled InverseProblems, is eager to publish more as-tronomical applications of inversetheory, and is planning a special issueon astronomical inverse problems inthe next year or so. John, a memberof the editorial board of the journal,

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encouraged the Team to submit papersand/or volunteer to contribute to thereview issue.

As some of the more senior Teammembers may recall, last year theTeam planned to coordinate a two-dimensional Hare and Hound exercise.For various technical reasons, this ex-ercise did not take place last year, butit is now ready to begin. Interestedparties will be able to find instructionsfor the exercise below. Frank Hill33333333333333333333333333333333

Magnetic Effects

Jack Harvey queried the members ofthe Magnetic Effects Team as to theirview of the consequences of theGONG decision to take only one mag-netogram per site per hour. The teamwas re-assured by his statement thatmore frequent magnetograms would bebe possible during “campaigns”. DougBraun emphasized that the magneto-grams could be used with p-mode datato study acoustic power deficits pro-ceedings the emergence of active re-gions.

Bernie Roberts reminded us that asimilar comparison of data would beuseful in studying p-mode frequencychanges induced by magnetic fields.This could be particularly useful forthe study of the structure of the atmos-pheric canopy field. Ted Tarbellpointed out the surprising result thatthe f-mode showed no frequencychange between canopy and non-canopy ( weak field ) regions. Thisresult certainly merits further study.Roger Ulrich argued for the highestpossible quality magnetograms.Phil Goode33333333333333333333333333333333

Mode Physics

Approximately 40 people attendedthe meeting of the Mode PhysicsTeam. This team has not been as

- 20 -33333333333333333333333333active as its importance deserves dur-ing the past two years since it has hadno leader. This year’s meeting was areflection of that problem. Once againthe meeting was chaired by the GONGproject liaison, Jack Harvey. One ofthe main agenda items was to find anew leader for the team. Happily,after the meeting, Roger Ulrich volun-teered to do this job in addition to hismany other activities in the GONGproject.

The meeting began with a review ofthe previous team meeting in Tucson(see Newsletter 17). Most of the re-maining time was spent discussing theimpacts of removing some featuresfrom the GONG instrument and thedata reduction pipeline. Jack Harveypresented the list of potential instru-ment changes in the form of pro andcon arguments from a scientific per-spective. These issues are discussed insome detail in the Instrument Updateelsewhere in this Newsletter and willnot be repeated here. The team wasmost concerned about lack of magneticfield information in helping to under-stand the physics of how modes in-teract with surface and submergedmagnetic field structures. This discus-sion was taken by the project as adviceto maintain a magnetograph capability.Another issue that received a lot ofdiscussion was the need (or not) forsquare pixel geometry and the relatedneed for tracking of the rotating solarimage. That discussion did not pro-duce a clear consensus of advice to theproject.

The final discussion of instrumentchanges centered on the effect oflong-term drift of the velocity zeropoint on mode frequency measure-ments. In the absence of a referencelaser, there was concern about howdata will be merged from one site toanother, and how low frequency oscil-lations and slow flows might be de-graded. It was agreed that short periodoscillations (i.e. p modes) should notsuffer from the loss of a stable refer-ence signal.

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Other instrumental issues were notjudged to be obviously significant tothe study of mode physics. There wasconcern about current plans to not pro-cess data for the study of low frequen-cy oscillations beyond the productionof temporal averages of the velocitydata.

The meeting ended abruptly whenthe temporary chairman called againfor volunteers to lead the team in thefuture. Jack Harvey[ Editor’s Note: Roger Ulrich very kindly

volunteered to chair the Mode Physics Team

after the Team Meeting, and he has

contributed the following report. ]

I am happy to accept the additionalresponsibility for this area of studysince I believe there are a number ofimportant questions yet to be answeredrelated to mode physics. Sample prob-lems include: the energy flow throughthe modes, the effects of magneticfields and spectral line formation in thepresence of various oscillation veloci-ties and temperature fluctuations. Iwould like to thank Jack for his tem-porary service in leading this groupalong with his very substantial dutiesas the principal magician in makingthe instrument work. We as a com-munity have the responsibility to con-tribute to the scientific analysis so thatwhen the network begins operations,we will quickly derive enough excitingscience to support the case for a exten-sion of the time coverage. Althoughthe mode physics problems are not thecore objectives of the GONG program,there is nonetheless a high probabilityof exciting discoveries here. We needto be ready with the right tools tomake these discoveries early.

Specific questions:Can we used phase relations

between the amplitude modulation pa-rameter, intensity and velocity to learnabout energetics?

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Can we plan co-ordinated high timerate coverage between the GONG in-strument and a magnetograph to studyMHD problems on selected areas ofthe solar surface?

What work is available on the fulltime-dependent line transfer problemin the presence of waves and oscilla-tions?

I will be happy to facilitate discus-sion of these and related questions bye-mail or other means so that we canhave a productive team meeting nextspring. Roger Ulrich33333333333333333333333333333333

“Low & Slow”

[ Editor’s Note: The Low Frequency Team

and the Nearly Steady Flows Team met to-

gether as in years past. They have filed this

joint report. ]

Our discussion focused on severalproposed GONG descope options thatimpact the science goals of the teams.

Elimination of Stabilized LaserThe basic problem is that laser calibra-tion is less constant than the solar cali-bration, at least on the short term.This probably has the greatest impacton the low frequency investigationsand is a serious problem, but hopefullynot lethal. It is probably worth keep-ing the laser calibration even with ahigher noise level, to monitor longterm trends in the instrument.

Elimination of Camera RotationWhile everyone would prefer squarepixels, there seemed to be no funda-mental objection to rectangular pixels,at least in the absence of image rota-tion. Having a rotating image intro-duces several sources of uncertaintyand may simply push the difficultyfrom hardware to software. There wasa strong consensus that the camerashould rotate.

- 21 -33333333333333333333333333No MagnetogramsEveryone would lament the loss of themagnetogram dataset. This is in partbecause of its intrinsic value and inpart because it is uncertain whethermodulation and intensity data alonecan be used to construct an adequateproxy. This question should be stu-died. Even if the blotches, fringes,and digitizing errors can not be solvedcompletely, the group felt that MGM’sshould be produced on a best effortbasis.

No Measurement of Distant ScatteredLightWhile not of photometric quality, mostpeople felt that near Sun measure-ments of the scattered light in thecorners of the CCD should be suffi-cient for determining the scatteringkernel. This will eliminate the needfor a mechanism and shorten the hour-ly calibration procedure.

No Processing of Low & Steady Pipe-line Past Production of 10 Minute SiteImagesTime constraints are limiting theamount of effort programmers canspend on the non p-mode analysis.While people are disappointed thatmore fix cannot be done, this does notpresent an insurmountable obstacle.Efforts should be made to push theprocessing as far as consensus permits.This might include image restoration( see below ) or more. Perhaps theteam should volunteer to develop aconsensus method for the otheranalysis steps — e.g. limb figure, rota-tion removal, remapping, SHT analysisand so on. 10 minute averages willhave to be constructed from registeredsingle site images. Averages shouldbe gaussian averages constructed from20 minutes of data on 10 minutecenters ( for p-mode detrending aswell ). Enough information character-izing the images must be readily avail-able so that investigators can performa reasonable merging of the data. Themerging can probably be left to indivi-duals [editorial comment — I think

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GONG will want to have at least onestandard merged data set].

No Image RestorationWhile cut with the rest of the pipelineanalysis, this should probably be doneto the 10-minute averages. The pro-gram exists and is probably fastenough for the reduced cadence datasets. This may affect the discussion ofitem 5, above, but probably not.

No MergeThis is most critical for low frequencyanalysis. Most people at the meetingseemed comfortable developing theirown merging strategy. It is importantthat data quality information be easilyavailable so intelligent merge decisionscan be made by anyone reducing data.The project will probably want to havea default merge algorithm for use inproducing movies, synoptic charts,etc…

While not all of these descopes willbe implemented and not all are irrever-sible, it is clear that the project doesnot have sufficient resources to doeverything. We need to carefullyevaluate the outstanding questions andprovide feed back. Can we form asmall working group to develop a con-sensus “pipeline” that is simpleenough to implement?J. Todd Hoeksema3333333333333333333333333333333333333333333333333333333333333333

DMAC Users Committee

The DMAC Users Committee hadtwo meetings at the 1992 GONGWorkshop, the first was an organiza-tional meeting and the second wasopen attendance at the DRAT Meeting.

In the organizational meeting, FrankHill, the GONG Data Scientist andDUC advisee, presented the Project’sresponse to the DMAC Review Panelreport. He also outlined major taskswhich the DMAC programming staffwill be working on in the near future.They are (not in prioritized order):

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A new release of GRASP in January1993

Support instrument development byprocessing prototype data

Begin pipeline integration and quali-ty control development

Develop standard test data sets forvalidation of pipeline

Continue development of: DSDS &User interface, merging algo-rithm, image restoration, efficientpeak finding, image culling, anddetrending

In the executive session that fol-lowed, the committee discussed itscharge, its style, potential action items(c.f. the DMAC Review Panel Report)and a next meeting date and place,likely October 2nd or 9th in Tucson.

After screening the team meetings,some of the potential action items forDUC are:

Priority of science data products,such as: magnetograms, furtherlow frequency and steady flowprocessing (e.g. scattering correc-tion and merging), m-averagedpeak finding

Impact of rectangular pixels andloss of image rotation and lasercalibration on data products

DSDS Interface: availability of en-gineering data and quality infor-mation

Priority of DMAC augmentations,e.g. image restoration

Interoperability between GONG andSOI

There were indications in the LowFrequency and Steady Flows, the Mag-netic Effects and the Data Reductionand Analysis Team Meetings that sub-teams might form to address some ofthese issues.

The members of DUC solicit thegreater GONG community for reac-tions to the Project’s baseline plan.It’s about 18 months to fielding of thenetwork. Plans for the initial DMACare firming up and the priorities for itsevolution over its three year operatinglife are being decided. Contact amember of DUC today!

[ Editor’s Note: The DUC met in Tucson on

- 22 -33333333333333333333333333Residuals

Figure 1

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October 2, and will meet again on January

29. ] Tuck Stebbins3333333333333333333333333333333333333333333333333333333333333333

Time SeriesInterpolation Schemes

As is well known, at Birminghamwe have oscillations data stretchingback over many years and from vari-ous stations. Originally the level of au-tomation was very low but as we haveexpanded the network we have greatlyincreased the automation. This has ob-vious advantages but also has disad-vantages. One problem that we havehad to face is that our clocks drift andwe have had to interpolate the data tomesh data from different stations.This article will discuss the interpola-tion procedures and will leave foranother occasion questions of the accu-racy of synchronization and how wetell what the timing errors are anyway.

Interpolation involves using a sim-ple function, of very low order com-pared with the number of data points,to estimate the value of a functionbetween the existing sample points. Ihave tested three different interpolationfunctions: a simple parabola, cubicspline and a truncated sinc function.Interpolation, by definition, involves adegree of smoothing and can be ex-pected to multiply the spectrum bysomething which changes both the am-plitude and phase of the fourier com-ponents. There is a further problemthat noisy data exacerbates the prob-lem. The data on different days andfrom different stations need to be prop-erly phased if they are to be transform-ed efficiently.

I tested the interpolating functionstheoretically using digital filteringtheory and have also interpolated dataof various qualities. Some details aregiven below and there is an internal re-port which I am happy to send to any-one who wants it. However, the bot-tom line is that if you are interested indata in the upper half of the spectrumthen neither cubic spline nor parabolic

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interpolations are adequate and a sincfunction ( truncated to 6 terms on ei-ther side of the centre ) is better.

To illustrate the point, consider thesingle day of data from Haleakala

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shown below ( Figure 1 ). The graphshows the power spectrum as a func-tion of frequency in microHertz. Inorder to investigate the effects of inter-polation, I recalculated the raw data at

- 23 -33333333333333333333333333

Figure 3

Figure 4222222222222222222222222222222222222222222222222222222222222222222221111111111111111111111111111111111111111111111111111111

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various offsets using the different in-terpolation schemes and then com-pared the fourier transform of the datawith the fourier transform of the origi-nal set. I was interested in anychanges in the computed power andany phase shifts which would presentproblems when I merged the data.

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Clearly, when I interpolate the data, Iexpect to see a linear phase shift dueto the new starting position, so I havesubtracted that from the data.

The next graph shows the phase er-rors in degrees for parabolic and splineinterpolation for the Hawaiian data( Figure 2 ) and following that the

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same thing for a sinc function forartificial data ( Figure 3 ) computed fordifferent amounts of time shift in unitsof 1 sample. ( Note that the sinc func-tion is apodized an well as truncated ).Even the sinc function does not giveperfect reproduction but it is good upto 9 mHz. Notice too that the phaseerror tends to some extent to showstructure where the spectrum itself isweak. The effect on the power isshown in the next 2 graphs. First isthe parabolic and spline for artificialdata ( Figure 4 ) and then sinc functioninterpolated Hawaiian data ( Figure 5,page 24 ). In these cases the power inthe interpolated spectrum is divided bythe power in the original spectrum.Yvonne Ellsworth3333333333333333333333333333333333333333333333333333333333333333

Instructions for theTwo-Dimensional Hounds

In 1988, the Inversions team of theGONG Project conducted a “Hare andHounds” experiment. In this exercise,Douglas Gough played the role of“hare” by computing theoretical rota-tional splittings from a standard solarmodel and an underlying rotationcurve that only he knew. The splittingsand the corresponding kernels werethen distributed to a pack of “hounds”,inversion enthusiasts who sought tocorrectly infer the unknown rotationrate. The exercise was a great success,and the interested reader can perusethe extensive report that appeared inthe September 1988 issue of theGONG Newsletter (#9).

That first exercise was a one-dimen-sional problem, i.e. the rotation ratewas dependent only on depth, and wasindependent of latitude. Matters haveprogressed, and the Inversions Teamhas just begun a new two-dimensionalHare and Hounds exercise in whichthe rotation rate varies with both depthand latitude. Recently, an e-mail mes-sage announcing the call to the huntwas sent to the potential players listedbelow. If you would also like to

- 24 -33333333333333333333333333

Figure 5

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participate, you may do so by follow-ing the directions below. Please alsocontact F. Hill if you plan to respondto the horn, so that we may be awareof your participation.

The list of potential hounds chasingthe 2-D hare includes: R. Barrett M.Brodsky, J. Brown, J. Christensen-Dalsgaard, P. Goode, D. Gough, S.Horner, F. Hill, S. Korzennik, A. Ko-sovichev, E. Lavely, P. Milford, M.Ritzwoller, R. Rosner, P. Scherrer, J.Schou, T. Sekii, H. Shibahashi, P.Stark, A. Thompson, M. Thompson, J.Toomre, P. Wilson

The object of this exercise is for theHounds to use the information provid-ed by the Hare (Douglas Gough) toinfer the two-dimensional rotationcurve Ω( r, θ ) from the data. TheHare has constructed three files thatcontain the information provided to theHounds.

gong_csp_coarse.dat contains theindependent variable mesh, the densi-ty, and the sound speed in the solarmodel. The format is:

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First line: number of points in themesh (501)lines 2-502: A counter I, the meshr/R density (cgs), Sound Speed (cgs)

The total size of this file is 40587Bytes.

efkp_004_nomesh.dat contains theeigenfunctions of 1380 oscillationmodes. The data for each mode is con-tained in sections of 502 lines. Theformat is:

First line: l , n, ν (mHz)lines 2-502: ξ, η, L where ξ is thevertical component, η is the hor-izontal component of the eigenfunc-tion, and L = (l (l +1))

1/2.The total size of this file is 20,161,800Bytes.

splt_gong_20mar_noerrs.dat con-tains the splittings for 69,662 modes.Despite the name of the file,normally-distributed noise has beenadded to the splittings. However, theHare has decided not to provide thestandard deviations of the noise at thistime. The format of the file is:

First line: number of modes (69662)lines 2-69663: l , n, m, ν (mHz), β

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splitting (nHz), where β is the in-tegral of the rotational splitting ker-nel for the mode.

The total size of this file is 3,134,796Bytes.

The data has been placed on theNOAO anonymous ftp disk. To accessthis data, use the FTP utility with thefollowing inputs:

host: robur.tuc.noao.edu or

140.252.1.10

ftp login: anonftp

ftp password: guest

cd gong

cd handh

get gong_csp_coarse.dat

get splt_gong_20mar_noerrs.dat

get efkp_004_nomesh.dat

bye

If you must use NSI/DECnet ( former-ly SPAN ), the location is

noao::ga0:[ftp.gong], or

5355::ga0:[ftp.gong]

(i.e., gazero.)

The total size of the data set isabout 23.3 MB; at a 56 kb transfer rateit should take about one hour totransfer. If you have absolutely no ac-cess to electronic transfer, contactFrank Hill with information on yourdesired tape medium.

If you plan to participate in this ex-ercise, please notify Frank Hill at theabove address. We anticipate that acomparison of results will occur at the1993 GONG meeting. To facilitate andencourage this goal, we have set adeadline of February 15, 1993, for aprogress report from all participatingPacks of Hounds.

In order to directly compare resultswith a minimum of headache, we re-quest that the results of your inversionbe plotted on the supplied mesh in theradial direction, and on a mesh in θ of251 points (250 intervals) evenlyspaced in latitude from -90 to +90 de-grees. The physical dimensions of theplot should be 15 × 15 cm (on tran-sparency material). The data should bedisplayed as a contour plot, in units ofnHz in a sidereal reference frame.There should be 11 contour levels (10

- 25 -33333333333333333333333333intervals) from 300 to 500 nHz. Notethat these contour levels may be re-vised after the February 15 status re-port. Frank Hill3333333333333333333333333333333333333333333333333333333333333333

Data Distributionand Publication Policy

I. Objectives

GONG is a collaborative project tomake definitive helioseismic observa-tions and to reduce, analyze and com-municate the results. The basis forparticipation in the GONG investiga-tion is through active membership inone, or more, of the GONG teams.This Data Distribution and PublicationPolicy is intended to encourage activeparticipation and to ensure equitablerecognition of contributions.

In order to achieve the full potentialof GONG, we must ensure that a broadrange of investigations is pursued byour distributed community. There willbe no long-term exclusive rights toGONG data. For this to succeed, wemust implement some elementarycommunication and review procedures,which encourage participation and donot stifle creativity. The following isintended to achieve this.

II. Data Distribution

II.A Data Policy

“The initial publication of the pa-pers presenting the data, the methodsby which they are acquired and pro-cessed, and the immediate scientificimplications shall be authored by theMembers of that Team directly respon-sible for the contents of the paper.The data shall be available solely tothe Teams until these assessments aremade within the first year, andthereafter the data shall be made avail-able to any qualified scientist. Thebroad contents of the papers shall bedetermined by mutual agreement be-tween the Teams to avoid unnecessary

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duplication.” ( GONG MembershipPlan, § 4: Publication and Data Ac-cess. GONG Newsletter #3, December1986 ) That is to say, data will only beavailable to active members of GONGfor the first year following data availa-bility, which will be announced in theNewsletter (and we anticipate on anelectronic bulletin board). TheMembers will already have submitteda Membership application with theiroriginal scientific objectives.

II.B Data Request

Specific data should be requestedfrom the project using a Data RequestForm which includes descriptions ofboth the scientific objectives and thedata requested. An activity will be as-signed to a Team to assure that coordi-nation and collaboration with similarinvestigations occurs. Provided thatthe applicant is an active member, thedata request will be satisfied unlessmore data is requested than is ap-propriate for the proposed investiga-tion. ( We may be forced to prioritizethe servicing of very large requeststhat tax the Data Storage and Distribu-tion System’s capabilities. ) The “Sci-entific Objectives of Proposed Work”and “Data Requested” are intended tobe 75 words or less, and they will bepublished in the GONG Newsletter( and we anticipate making them avail-able electronically, as well ).

II.C Progress Report

For an investigation to remain ac-tive, a brief ( 75 words or less )progress/activity report will be re-quired for the GONG Newsletter everysix months. Presentation of work inprogress will be a major item of busi-ness of the Annual GONG Meetingand Team meetings. The intent is toshare intermediate results, stimulatecollaborative work where appropriate,and to avoid unproductive, competitiveactivities.

II.D Coordinating Committee

A Coordinating Committee, consist-ing of the Scientific Advisory

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Committee and the Team Leaders, willoversee the progress of the various in-vestigations and encourage the princi-pal data reduction and analysis tasksdeveloped by the Teams. The Coordi-nating Committee will periodically re-view these policies.

III. Publication Process

III.A Notice of Intent to Publish

Prior to submission for publicationor presentation of results utilizingGONG data, a brief “Intention to Pub-lish” — essentially the paper’s abstract— must be submitted, for publicationin the GONG Newsletter ( plus elec-tronic availability ).

III.B Internal Reviews

A copy of the paper must be madeavailable for a Technical/InstrumentalReview by Project personnel, to helpavoid misunderstanding or confusionover potentially known instrumental orprocessing artifacts, as well as a TeamScientific and Coordination Review tobe overseen by the Coordinating Com-mittee. This latter Review will be si-milar to many institutions’ internal re-viewing procedures — it must be rapidand not significantly delay publication,and is intended to provide collegial ad-vice and clarification, not an obstacle.The box on page 27 contains a check-list to be completed prior to publica-tion.

III.C GONG Acknowledgement

All publications based upon GONGdata must — according to our obliga-tions to the NSF — contain the follow-ing footnote or acknowledgment:“This work utilizes data obtained bythe Global Oscillation Network Group( GONG ) project, managed by the Na-tional Solar Observatory, a Division ofthe National Optical Astronomy Ob-servatories, which is operated byAURA, Inc. under a cooperative agree-ment with the National Science Foun-dation.” For network data, authorsshould also include the following:“The data were acquired by

- 26 -33333333333333333333333333GONG Data Request

Requester names: 3333333333333333333333333333333333333333333

Program Title: 3333333333333333333333333333333333333333333333

Program #, Date Received: 33333333333333333333333333333333333(to be filled in by Project)

Scientific Objectives of Proposed Work:

Data Requested:

Potential Collaborators: 33333333333333333333333333333333333333

Related GONG Programs: 333333333333333333333333333333333333

Cognizant Team:5 Reduction & Analysis5 Inversions5 Models5 Mode Physics5 Low Frequency5 Magnetic Effects5 Nearly Steady Flows & Magnetic Fields5 None seem to Apply

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instruments operated by the BBSO,HAO, LMSO, USO, IAC, and CTIO.”

IV. Project Phases

We can already identify severaldifferent phases for the GONG dataand hence somewhat different sorts ofpublications.

IV.A Project-Produced Instrument andData Processing Articles

These will consist of archival refer-ences to support the scientific articleswith descriptions of the instrument’sand data processing system’s nominalperformances. They will have largeauthorship lists consisting of GONGproject personnel and GONG Memberswho have made significant contribut-ions. There have already been anumber of descriptive articles aboutthe Project. The first of these to con-tain real data will describe the GONGsite survey and its results.

IV.B Prototype Data

GONG data has already been ob-tained to support instrument develop-ment. The prototype instrument willproduce science grade data prior to fullnetwork operations. It is GONG’s in-tention to provide this prototype datato a broad community in order to stim-ulate understanding of the instrumentand the data processing, as well as togenerate new knowledge. This GONGcommunity participation and oversightcontributes significantly to the devel-opment of the instrumental, data pro-cessing and distribution aspects of thedata. It will also exercise the Teamsand Coordinating Committee, as wellas these Publication Policies prior tonetwork operations. We want the datato be used as soon as it is useful.

IV.C GONG Symposium ( first networkresults )

The first publication of GONG fullnetwork data and analysis will befocussed by a Symposium to highlightTeam activities and result in the land-mark, refereed publications. To en-courage initial team activities and

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avoid unproductive rushing to publica-tion, the initial results of the Team ac-tivities — and once again all work atthe outset will be under the auspices ofthe Teams — will appear at a “GONGSymposium” to be held nominally oneyear after first light from the full net-work. It is intended that the articles berefereed prior to publication togetherin an archival journal.

Authorship of these initial paperswill consist of all those having made a

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substantial contribution to the researchpresented in the publication, includingkey GONG Project personnel and (atleast) one representative from each ofthe sites operating network instru-ments.

We anticipate that in addition to theGONG Symposium papers, there willbe an initial series of papers publishedabout one year after first light in abroad circulation journal, such as Na-ture or Science, that will contain the

- 27 -33333333333333333333333333GONG Publication/Presentation Release Checklist

5 Authors’ Names: 33333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333

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5 Program Title and Number: 3333333333333333333333333333333333333333333333333333333333333333333333333333

5 Publication/Presentation Title: 33333333333333333333333333333333333333333333333333333333333333333333333

5 To be submitted/presented to: 33333333333333333333333333333333333333333333333333333333333333333333333

5 Anticipated submission/presentation date: 33333333333333333333333333333333333333333333333333

5 GONG Membership

5 Data Request

5 Newsletter Abstract of Data Request: 3333333333333333333333333333333333333333333333333333333333

5 Newsletter Progress Reports: 333333333333333333333333333333333333333333333333333333333333333333333333

5 Newsletter Abstract from Notice of Intent to Publish: 33333333333333333333333333333333

5 Project “Artifact” Review

5 Team Review

5 GONG Footnote Acknowledgement

5 Contributions to GONG: 3333333333333333333333333333333333333333333333333333333333333333333333333333333333

5 Other GONG Programs by Authors in progress: 3333333333333333333333333333333333333333

5 GONG Publications: 3333333333333333333333333333333333333333333333333333333333333333333333333333333333333333

5 Related GONG Programs: 333333333333333333333333333333333333333333333333333333333333333333333333333333

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first data, including mode frequencies,as well as results from the Team ac-tivities. We accept the possibility thatsome “hot results” could merit recon-sideration of the first-year publicationembargo, or that DMAC processing de-lays could suggest an extension. Han-dling of such an eventuality would beoverseen by the Coordinating Commit-tee.

IV.D “Ever After”

Following the first year, GONG datawill be made available to the broadcommunity while Team membershipwill continue to be strongly encour-aged. All data requests will be an-nounced and assigned to Teams andcoordination assured through the Coor-dinating Committee. Whereas author-ship for the earlier phase papers willbe very extensive, authorship through-out the remainder of the Project willbe basically those responsible for theincremental work. However, theTeams will continue to function, andwe anticipate that they will organizeWorkshops and continue to encouragecollaborative analysis of the GONGdata products.

3333333333333333333333333333333333333333333333333333333333333333GONG 1992

SEISMIC INVESTIGATIONOF THE SUN AND STARS

orThe View From Boulder

August 10-14, HAO hosted the an-nual meeting of the Global OscillationNetwork Group (GONG). In pastyears, NSO has always hosted the an-nual GONG meeting in Tucson. Thisyear, however, it was decided that theproject had developed to the point thatthe annual gathering should be in theform of a regular scientific meeting,held in some other location. Also, itwas felt that the scientific concern ofthe meeting should be broadened to in-clude discussion of multi-mode pulsa-tions in stars other than the Sun. Theresult was this year’s meeting, “GONG1992: Seismic Investigation of the Sun

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and Stars,” hosted by HAO and spon-sored jointly by NCAR, HAO, andNSO.

With 129 attendees from more thana dozen countries, this gathering wasnot only an exciting scientific event,but also an opportunity for HAO toshow off its new facilities to its friendsworldwide.

The meeting’s focus was providedby an outstanding series of invitedtalks, covering a range of topics relat-ed to the seismology of the Sun andstars, as well as to the basic physics ofstellar interiors. Adding to the scienti-fic pleasures were the ninety-odd con-tributed poster papers, many of themannouncing new and exciting results.Considerable time was allotted for dis-cussion of the talks and posters, andfor meetings of the GONG teams andvarious other special interest groups.The largest of these, (occupying the

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entire day before the main GONGconference) was devoted to the annualSOI/MDI team meeting. Both the in-vited talks and the poster papers willappear in the meeting proceedings,which are to be published as part ofthe A.S.P. Conference Series. Socialactivities included a reception at theNCAR Foothills Lab, and a banquet(graced with a full moon, not to men-tion Peter Wilson’s hitherto untold ex-planation of the meaning of GONG) atthe NCAR Mesa Lab. Throughout theweek, whether discussing seismologyin general or the specifics of GONG orSOI, the same two thoughts tended toemerge: (1) progress is being made ata terrific rate, and (2) there is still agreat deal to do.

- 28 -33333333333333333333333333Data Distribution and Publication Procedures

1)Data Availability Announced

2)Data Request Submitted to Project

3)Activity Assigned to a Team

4)Data Delivered

5)“Scientific Activity” and “Data Delivered” Announced in Newsletter

6)Biannual Activity Reports Published

7)Presentation at GONG Annual Meeting

8)Publication/Presentation Release submitted for Publication Reviewby Team ( for Scientific Coordination ) and Project ( for instrumentaland data processing considerations )

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Invited Talks

Norman Murray (California Institute ofTechnology) “The Excitation of Solarp-Modes”

Michael J. Thompson (Queen Mary &Westfield College, London) “SeismicInvestigation of the Sun’s InternalStructure and Rotation”

Pawan Kumar (High Altitude Observatory)“Waves with Frequencies Above theAcoustic Cutoff Frequency”

Forrest Rogers (Lawrence LivermoreLaboratory) “Equation of State andOpacity of Stellar Plasmas”

Werner Dappen (University of SouthernCalifornia) “Theory of delta Scuti Stars”

Jaymie Matthews (University of Montreal)“Observing the Eigenmode Spectra ofroAp and delta Scuti Stars”

Donald Winget (University of Texas) “TheWhole Earth Telescope”

Thierry Appourchaux (ESA/ESTEC) andDouglas Gough (Cambridge University)“PRISMA: The First Space Mission toLook Inside the Stars”

J. Harvey, F. Hill, J. Kennedy, and J.Leibacher (NSO) “GONG ProjectUpdate”

Jeffrey Kuhn (Michigan State University)“What Causes Cycle-Related GlobalSolar Changes?”

Barry LaBonte (University of Hawaii)“Seismology of Solar Active Regions”

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Poster Papers

Andersen, B. & Andreassen, Gravity Waveand Convection Interaction in the SolarInterior

Anderson, E., Gap Filling the GONG DataSet

Antia, H. & Chitre, S., Mesogranulation asa Solar Convective Eigenmode

Bachman, K., Schou, J. & Brown, Obser-vations of Intermediate Solar Oscil-lations: April-June, 1989

Barrett, R., On the Optimal Choice ofRegularization Parameter for the Inver-sion of Solar Oscillation Data

Belmonte, J. & and the STEPHI Team,STEPHI 92: BN & BU Cancri, twoScuties in the Praesepe Cluster

Bogart, R., Hill, F. et al, Artificial Data forTesting Helioseismology Algorithms

Bogdan, T., Brown, T. et al, TheAbsorption of p-modes by Sunspots:Variations with Degree and Order

Braun, D., LaBonte, B. et al, The p-modeScattering Properties of a Sunspot

Brown, T., Data Merging Techniques forAstero- and Helioseismology

Brummell, N., Hurlburt, N et al, TurbulentCompressible Convection with Rotation

Chang, H. & Gough, D., On the Determin-ation of the Temporal Properties of FreeOscillations

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Chaplin, W., High Precision Velocity andMagnetic Measurements of the StarProcyon (F5 IV-V)

Christensen-Dalsgaard, J., On the Astero-seismic HR Diagram

Christensen-D, J. & Thompson, A Hands-on IDL Program for Helioseismic Inver-sion

Davies, A., Avalanche Photodiodes inStellar Spectroscopy

Delache, Ph., Gavryusev, et al, TimeVariations of Solar Acoustical ModeFrequencies, Radius and NeutrinoCounting Rate

Demarque, P., Guenther, et al, A Limit onthe Variability of G from Helioseismol-ogy

Dumbill, A., Measurements of the Longi-tudinal Component of the SolarMagnetic Field

Duvall, T., Jeffries, S. et al, Asymmetriesof Solar Oscillation Line Profiles

Dziembowski, W. and Goode, P., SeismicLimits on the Sun’s Internal ToriodalField

Dziembowski, W. and Goode, P., TheSun’s Internal Angular Momentum fromSeismology

Dziembowski, W. and Goode, P., TheSun’s Internal Rotation During and afterthe 1986 Activity Minimum

Fan, Y., Fisher, G & Deluca, E., TheOrigin of Morphological Asymmetries inBipolar Active Regions

Fernandes, D, Scherrer, et al, HighFrequency and High Wavenumber SolarOscillations

Genovese, C. & Stark, P., l-1 SpectralEstimation: Algorithms and Tests of“Superresolution”

Gilliland, R., Brown, et al, M67 StellarOscillations: CCD Ensemble Photometryon a Network of 4m Telescopes

Gough, D. & Kosovichev, A., SeismicAnalysis of Stellar p-mode Spectra

Gough, D., Merryfield, Toomre, Inversionfor Background Inhomogeneity fromPhase Distortions of One-DimensionalWave Trains

Gough, D. & Novotny, E., AsteroseismicCalibration of Stellar Clusters

Gough, D. & Sekii, T., On the Detection ofConvective Overshoot

Gough, D. & Stark, P., Are the 1986-1988Changes in Solar Free- Oscillation Split-ting due to Sunspots?

Gouttebroze, P. & Toutain, OscillationMode Visibility: An Eulerian Approach

Guenther, D. & Demarque, Seismology ofProcyon

- 29 -33333333333333333333333333Harvey, J., Duvall, et al, Chromospheric

Oscillations and the Background Spec-trum

Harvey, J. et al, GONG Instrument Devel-opment

Hathaway, D., Doppler Measurement ofthe Solar Meridional Circulation

Horner, S & Brown, T., The Search forPulsations in Late-Type Giants: Prelim-inary Results

Jain, R. & Roberts, B., P-mode FrequencyShifts and Chromospheric Magnetism

Johnston, A., Wright & Roberts, AModified Bohr-Sommerfeld Conditionfor p-modes

Jones, a. et al, Observations of delta ScutiStars from Aarhus

Jones, a. et al, A Simple Multi Color CCDPhotometer

Jones, P., Merryfield & Toomre,Interaction of Externally-Driven Acous-tic Waves with Compressible Convec-tion

Kelly, J & Ritzwoller, M., Observing GiantCell Convection with Helioseismic Line-widths

Kennedy, J, Jeffries & Hill, Solar g-modeSignatures in p-mode Signals

Kennelly E, Merryfield et al, ModeIdentification in delta Scuti Stars byFourier Analysis of Line-Profile Varia-tions

Komm, R., Harvey & Howard, TorsionalOscillations and Internal Rotation

Kopp, G., Helioseismic Prospects in theMid-Infrared

Korzennik S, Rhodes & Johnson, Helio-seismology on a Massively ParallelArchitecture: Reduction of 1024 by 1024Full-Disk Dopplergrams on Intel’sTouchstone Delta Supercomputer

Korzennik S, Cacciani & Rhodes, Towardsa Better Determination of FrequencySplittings at Intermediate and HighDegree: Preliminary Results of SectoralFrequency Splittings from a 90-dayObserving Run

Korzennik S. & Sabbey, Measurement ofthe Phase Relation Between Velocityand Intensity Fluctuations Induced bySolar P-Modes from GONG BreadboardData

Kotov, V. & Lyuty, V., A Puzzle of the160-min Periodicity in the Sun, RR LyrStars and AGN’s: the Signatures of aCosmological Origin?

Kotov, V, Scherrer, et al, The Search for160-min Oscillations in the Stanford andCrimean Solar Velocity Observations,1974-1991

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Lazrek, M & Hill, F., Temporal WindowEffects and their Deconvolution fromSolar Oscillation Spectra

Libbrecht, K. & Woodard, M., Helio-seismic Observations of the Solar Cycle1986-90

Libbrecht, K, et al, The form of theAngular Velocity in the Solar Convec-tion Zone

Lindsey, C, Braun, et al, Prospects inLocal Acoustic Diagnostics of Subsur-face Magnetic Structure

Merryfield, W. & Kennelly, E., FourierAnalysis of Variable Line Profiles

Milford, P., Hill & Tarbell, SubsurfaceTransverse Flows Near an Active Re-gion

Milford, P., Frank, et al, High Frequencyp-mode Spectrum

Monteiro, C-D & Thompson, On DetectingOvershoot Below the Sun’s ConvectiveEnvelope

Narasimha, D. & Roxburgh, ConvectiveOvershooting in Stars

Noyes, R. et al, The Advanced Fiber OpticEchelle Spectrograph for Asteroseismol-ogy

Palle, Perez-Hernandez et al, Observationsof Low Degree p-modes with Odd l+m

Patron, J., Hill, et al, Ring DiagramAnalysis of Mt. Wilson Data

Perez-Hernandez & C-D, The PhaseFunction for Solar-Like Stars

Peri, M. & Libbrecht, K., A New EchelleSpectrograph for Asteroseismology

Pijpers, F. & Thompson, M., FasterFormulations of the OLA Method

Pijpers, F. & Thompson, M., Inversions forthe Sun’s Rotation and its RadialDerivatives

Price, G., The Effects of Leakage into theSolar Atmosphere on Acoustic ModeProperties

Rast, M, Nordlund, et al, Ionization Effectsin Solar Granulation Simulations

Rast, M. & Toomre, J., Acoustic Genera-tion by Thermal Boundary Layer Insta-bility in a Partially Ionized Fluid

Regulo, C., Fossat et al, On Full DiskHelioseismology Power Spectra Aroundthe Cut-Off Frequency

Rhodes, E., Cacciani et al, Plans for Mt.Wilson-Crimean Astrophysical Observ-atory High-Degree HelioseismologyNetwork

Rhodes, E, Rhodes et al, Observations ofthe Thermal Response of the TerrestrialAtmosphere to the Eclipse of July 11,1991

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Rieutord, M., Coherent Structures and theDifferential Rotation of the Sun

Ronan, R. & LaBonte, B., High FrequencySolar Oscillations

Rosenthal, C & Gough, D., When is an f-mode not an f-mode?

Roxburgh, I., Seismology of the SolarEnvelope. The Phase Shift of Low lModes due to the Helium IonizationZone and the Base of the ConvectiveEnvelope

Roxburgh, I. & Vorontsov, S, Seismologyof the Solar Envelope: The Base of theConvective Zone as Seen in the PhaseShift of Acoustic Waves

Scherrer, P., Hoeksema & Kotov, On theUpper Limit for Detecting g-mode Os-cillations of the Sun

Schou, J, C-D & Thompson, Two-Dimensional Helioseismic Inversions

Sekii, T., On a 1 × 1-InversionTechnique for Solar Rotation

Tomczyk, S. & Veitzer, S., An Instrumentto Observe Low-Degree Solar Oscil-lations

Toner, C. & Jeffries, S., AccurateMeasurement of the Geometry for aFull- Disk Solar Image and Estimationof the Observational Point Spread Func-tion

Toutain, T. & Gouttebroze, VisibilityFunctions for Global Intensity Measure-ments

Ulrich, R., Observations of the Time-De-pendent Gravitational Redshift of the NaD1 Line

Ulrich, R. & Evans, S., Response of theSolar Atmosphere to Low FrequencyPerturbations

Ulrich, R. & Henney, C., Modeling ofIntegrated Sunlight Velocities due toSurface Darkening by Magnetic Fields

Veitzer, S, Tomczyk & Schou, Require-ments for the Observation of Low-Degree Solar Oscillations

Vidal, I & Belmonte, J., CCD Asteroseis-mology in the Open Cluster NGC6802

Wheeler, S., High Frequency SolarVelocity Noise

Williams, W, Hill, et al, Tests of SimpleGONG p-mode Merging Algorithm

Wilson, P., Forward Calculations forSeveral Classes of Iso-Rotation SurfaceModels

Woodard, M. & Libbrecht, K., SolarActivity and Oscillation FrequencySplittings

Wright, A. & Thompson, M., On theEffects of Chromospheric Magnetic Per-turbations on Solar Oscillation Frequen-cies

- 30 -33333333333333333333333333More Data Products Available

Four days of data acquired by the GONG Prototype instrument( August 30 and 31 and September 5 and 6, 1992 ) have beenreduced. These are “calibratable” data days and are comparable inquality to the June 8 and 9 1989 Breadboard days.

The reduced data products include:calibrated velocity, modulation, intensity imagesten-minute resampled velocity, modulation, and intensity imagestimes series of mode coefficientspower spectra of mode coefficientsl -ν spectra of mode coefficients

The ten-minute averages and the l -ν spectra are accessible on-lineon GONG’s anonymous ftp disk. ( Access instructions appear on page9 in this Newsletter ). The raw images, calibrated images, times seriesand power spectra are available on Exabyte cartridges.

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Participants

Bo N. Andersen, Norwegian Space Centre,Norway

Ed Anderson, National Solar Observatory

Thierry Appourchaux, ESA/ESTEC, TheNetherlands

David Armet, National Solar Observatory

Kurt Bachmann, High Altitude Observa-tory/NCAR

Lyle Bacon, Stanford University

Peter Bandurian, High Altitude Observa-tory/NCAR

Richard Barrett, Glasgow University, Scot-land

Juan Antonio Belmonte, Instituto de Astro-fısica de Canarias, Spain

Ira B. Bernstein, Yale University

A. Bhatnagar, Udaipur Solar Observatory,India

Richard S. Bogart, Stanford University

Thomas Bogdan, High Altitude Observa-tory/NCAR

Douglas C. Braun, University of Hawaii

Timothy M. Brown, High Altitude Obser-vatory/NCAR

John Brown, University of Glasgow, Scot-land

Nic Brummell, University of Colorado

Rock Bush, Stanford University

Bruno Caccin, Universit di Roma

Shelly Cadora, Stanford University

William Chaplin, Birmingham University,England

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Shashikumar M. Chitre, Tata Institute ofFundamental Research, India

Jørgen Christensen-Dalsgaard, Aarhus Uni-versitet, Denmark

Werner Dappen, University of SouthernCalifornia

Andrew R. Davies, Birmingham Univer-sity, England

Detlev Degenhardt, High Altitude Obser-vatory/NCAR

Andrew Dumbill, Birmingham University,England

Thomas Duvall, Jr., NASA/GSFC

Wendy Erdwurm, National Solar Observa-tory

Scott Evans, University of California, LosAngeles

Yuhong Fan, University of Hawaii

Peter Fox, High Altitude Observa-tory/NCAR

Soren Frandsen, Aarhus Universitet, Den-mark

Elena Gavryuseva, Instituto d’Astrofısicad’Canarias, Spain

Christopher Genovese, University of Cali-fornia, Berkeley

Ronald L. Gilliland, Space Telescope Sci-ence Institute

Peter Gilman, National Center for Atmos-pheric Research

Phil Goode, New Jersey Institute of Tech-nology

Douglas Gough, Cambridge University,England

Pierre Gouttebroze, Institut d’Astrophys-ique Spatiale, France

David Guenther, Yale University

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Deborah Haber, Colorado College

Fred Hall IV, University of Colorado

David H. Hathaway, NASA/MarshallSpace Flight Center

Jack Harvey, National Solar Observatory

Carl Henney, University of California, LosAngeles

Frank Hill, National Solar Observatory

Bradley Hindman, University of Colorado

Todd Hoeksema, Stanford University

Scott Horner, HAO/NCAR, University ofChicago

Rekha Jain, University of St. Andrews,Scotland

Stuart Jefferies, Bartol Research Institute

Vicki Johnson, Stanford University

Andrew Jones, Aarhus Universitet, Den-mark

Keith Julien, University of Colorado

Steven Kawaler, Iowa State University

John F. Kelly, University of Colorado

James Kennedy, National Solar Observa-tory

Edward J. Kennelly, University of BritishColumbia, Canada

Hans Kjeldsen, Aarhus Universitet, Den-mark

Rudolf Komm, National Solar Observatory

Greg Kopp, National Solar Observatory

Sylvain G. Korzennik, Harvard-Smithson-ian Center for Astrophysics

Alexander Kosovichev, University of Cam-bridge, England

Valeri A. Kotov, Stanford University

Jeffrey Kuhn, Michigan State University

Pawan Kumar, High Altitude Observa-tory/NCAR

Barry LaBonte, University of Hawaii

Mohamed Lazrek, CNCPRST, Morocco

John W. Leibacher, National Solar Obser-vatory

Ken G. Libbrecht, California Institute ofTechnology

Jaymie Matthews, Universite de Montreal,Canada

William Merryfield, University of Victoria,Canada

Barbara Mihalas, University of Illinois

Peter Milford, Stanford University

Mario Joao P.F.G. Monteiro, Queen Mary& Westfield College, England

Norman Murray, California Institute ofTechnology

- 31 -33333333333333333333333333D. Narasimha, Tata Institute of Fundamen-

tal Research, India

Rakesh Nigam, Stanford University

Eva Novotny, University of Cambridge,England

Robert W. Noyes, Center for Astrophysics

Pere L. Palle, Instituto de Astrofısica deCanarias, Spain

Jesus Patron, Instituto de Astrofısica deCanarias, Spain

Fernando Perez Hernandez, Instituto deAstrofısica de Canarias, Spain

Michal Peri, California Institute ofTechnology

Frank P. Pijpers, Queen Mary andWestfield College, England

James A. Pintar, National Solar Observa-tory

Martin A. Pomerantz, Bartol ResearchCorporation

Gary H. Price, SRI International

Mark Rast, University of Colorado

Clara Regulo, Instituto de Astrofısica deCanarias, Spain

Sergio R. Restaino, New Jersey Institute ofTechnology

Edward Rhodes, University of SouthernCalifornia

Michel Rieutord, Observatoire Midi-Pyrenes, France

Mike Ritzwoller, University of Colorado

Bernard Roberts, University of St. An-drews, Scotland

Forrest Rogers, Lawrence LivermoreNational Laboratory

Robert S. Ronan, University of Hawaii

Colin S. Rosenthal, University of Colorado

Ian W Roxburgh, Queen Mary andWestfield College, England

Luiz A.D. Sa, Stanford University

Kenneth Schatten, National Science Foun-dation

Philip H. Scherrer, Stanford University

Jesper Schou, HAO/NCAR, Aarhus Uni-versitet, Denmark

Takashi Sekii, University of Cambridge,England

Philip B. Stark, University of California

Robin Stebbins, University of Colorado

Margie Stehle, Stanford University

Ted Tarbell, Lockheed Palo Alto ResearchLaboratory

Michael J. Thompson, Queen Mary andWestfield College, England

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Steve Tomczyk, High Altitude Observa-tory/NCAR

Clifford Toner, National Solar Observatory

Juri Toomre, University of Colorado

Mark Trueblood, National Solar Observa-tory

Roger Ulrich, University of California, LosAngeles

Bar Varda, Hebrew University of Jerusa-lem, Israel

Ram Varma, Physical Research Labora-tory, India

Seth Veitzer, High Altitude Observa-tory/NCAR

Inmaculada Vidal, Instituto de Astrofısicade Canarias, Spain

Sarah Wheeler, University of Birmingham,England

Winifred E. Williams, National SolarObservatory

Robert Williams, Cerro Tololo Inter-American Observatory, Chile

Peter R. Wilson, University of Sydney,Australia

Donald Winget, University of Texas

Martin Woodard, California Institute ofTechnology

Andrew N. Wright, University of St. An-drews, Scotland

Igor Zayer, Lockheed Palo Alto ResearchLaboratory Tim Brown

3333333333333333333333333333333333333333333333333333333333333333GONG ’94

Roger Ulrich, Ed Rhodes andWerner Dappen have agreed to organ-ize and host the general scientificmeeting associated with the GONGproject in 1994 in the Los Angelesarea. Because this meeting comes justbefore the operation of several majorhelioseismology projects, it seems ap-propriate to have it sponsored as anIAU Symposium. Discussions are inprogress with several of the IAU Com-missions to obtain this sponsorship. Inorder to avoid a schedule conflict withthe holding of the IAU General As-sembly in August, 1994, this symposi-um will be held in mid-May, 1994. Atitle for the symposium of “Helio- andAstero-Seismology from the Earth andSpace” has been chosen. Roger Ulrich

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GONG Scientific Visitors

Mohamed Lazrek, from the CentreNational de la Recherche in Agdal-Rabat, Morocco, visted the GONGProject from May 15 through August15, 1992. During his visit, he workedwith F. Hill on developing and testinga deconvolution method to remove theresidual effects of the temporal win-dow from the power spectrum. Theresults were presented at the GONG1992 meeting, and a paper will be sub-mitted to Astronomy and Astrophysics.

D. Narasimha, from the Tata Insti-tute in Bombay, India, visited theGONG project from July 2 to August26, 1992. During his visit, he workedon an alternative method to decomposetwo-dimensional data into sphericalharmonics. A GONG Technical Re-port, No. 92-2, is currently in prepara-tion. Frank Hill3333333333333333333333333333333333333333333333333333333333333333

Theses

Congratulations to the followingrecent Ph.D.’s in helioseismology:

David Fernandes, Stanford University,“The Detection and Characterization ofHigh Frequency and High Wave-number Solar Oscillations”

Bernhard Fleck, Universitat Wurzburg,“Untersuchungen zur Dynamikoszillatorischer Vorgange in derSonnenatmosphare. (Studies on thedynamics of oscillatory motions in thesolar atmosphere)”

Matthew Penn, University of Hawaii,“The Source of Five-Minute PeriodPhotospheric Oscillations”

Robert Ronan, University of Hawaii,“Global Solar Intensity OscillationsNear Solar Maximum”

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Recent Preprints inHelio- and Astero-

seismology

The titles included here are preprintswhich have been sent, as a courtesy, tomembers of the GONG project staff.They are listed for the convenience ofNewsletter readers. Please contact theauthor(s) for additional information. Ifyou would like your preprint titles tobe included in future Newsletters, senda copy of your preprints to one of theGONG staff. If you would prefer thatyou preprint titles do not appear in theGONG Newsletter, please indicate thatwhen you send any of us a copy. Oth-erwise, we shall share it!

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Appourchaux, T., Gough, D., Hoyng, P.,Catala, C., Frandsen, S., Frohlich, C.,Jones, A., Lemaire, P., Tondello, G., andWeiss, W.: “PRISMA: A New SpaceMission for Stellar Physics”

Bahcall, J.N., and Pinsonneault, M.H.:“Standard Solar Models, With andWithout Helium Diffusion and the SolarNeutrino Problem”

Bahcall, J.N., and Salpeter, E.E.: “IsStellar Evolution Theory Wrong and theSolar Neutrino Problem Solved?”

Benkhaldoun, Z., Kadiri, S., Lazrek, M.,and Vernin, J.: “A Simple FluxIntegration Photometer for Day TimeSite Testing at Oukaimeden”

Braun, D.C., Duvall, T.L., LaBonte, B.J.,Jefferies, S.M., Harvey, J.W., andPomerantz, M.A.: “Scattering of p-Modes by a Sunspot”

Brodsky, M., and Vorontsov, S.V.:“Asymptotic Theory of Intermediate-and High-Degree Solar Acoustic Oscil-lations”

Brown, T.M., Christensen-Dalsgaard, J.,and Mihalas, B.W.: “How May Seis-mological Measurements Constrain Para-meters of Stellar Structure?”

Christensen-Dalsgaard, J.: “The Structureand Evolution of the Sun”

Christensen-Dalsgaard, J.: “Pulsation The-ory and Stellar Structure”

Christensen-Dalsgaard, J., Hansen, P. C.,and Thompson, M. J.: “GSVD Analysisof Helioseismic Inversions”

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Duvall, T.L., Jefferies, S.M., Harvey, J.W.,Osaki, Y., and Pomerantz, M.A.:“Asymmetries of Solar Oscillation LineProfiles”

Dziembowski, W.A., Pamyatnykh, A.A.,and Sienkiewicz, R.: “SeismologicalTests of Standard Solar Models Calcula-ted with New Opacities”

Edmonds, P., Cram, L., Demarque, P.,Guenther, D.B., and Pinsonneault, M.H.:“Evolutionary Models and the p-ModeOscillation Spectrum of α Cen A and B”

Evans, D.J., and Roberts, B.: “The Inter-pretation of Solar Cycle Variability inHigh Degree p-Mode Frequencies”

Fernandes, D.N., Scherrer, P.H., Tarbell,T.D., and Title, A.M.: “Observations ofHigh Frequency and High WavenumberSolar Oscillations”

Fossat, E.: “IRIS Data Merging. I. ASolution to Minimize the Low andIntermediate Frequency Noise”

Fossat, E., Reegulo, C., Roca Cortes, T.,Ehgamberdiev, S., Grec, G., Khamitov,I., Lazrek, M., Sanchez Duarte, L.,Gelly, B., and Palle, P.: “On the Acous-tic Cutoff Frequency of the Sun”

Frandsen, S.: “Asteroseismology from theGround”

Frandsen, S., Douglas, N., and Butcher, H.:“An Astronomical Seismometer”

Frandsen, S., and Kjeldsen, H.: “Observa-tional Constraints on Mode Excitation inδ-Scuti Stars in Open Clusters”

Gautschy, A.: “Exciting Alpha Cygni”

Glatzel, W., and Gautschy, A.: “TheTreatment of Highly Nonadiabatic Non-radial Pulsations by Application of theRiccati Method to the Example of HdCStars”

Gough, D.O., and Kosovichev, A.G.: “Is ItPossible To Determine Whether A StarIs Rotating About A Unique Axis?”

Gough, D.O., and Kosovichev, A.G.:“Initial Asteroseismic Inversions”

Gough, D.O., Kosovichev, A.G., Sekii, T.,Libbrecht, K.G., and Woodard, M.F.:“Seismic Evidence of Modulation of theStructure and Angular Velocity of theSun Associated with the Solar Cycle”

Gough, D.O., and Stark, P.B.: “Are the1986-1988 Changes in Solar Free-Oscillation Splitting Caused by Sun-spots?”

Guenther, D.B., and Demarque, P.: “Evo-lution and Seismology of Procyon”

Hasan, S.S., and Christensen-Dalsgaard, J.:“The Influence of a Vertical MagneticField on Oscillations in an IsothermalStratified Atmosphere”

- 33 -33333333333333333333333333Hill, F.: “On the Interpretation of Inver-

sions of Helioseismic Rotational Split-ting Measurements”

Jones, A.: “PRISMA - The Instruments”

Kalkofen, W., Rossi, P., Bodo, G., andMassaglia, S.: “The 3 Min Oscillationsin Chromospheric Bright Points”

Kosovichev, A., Christensen-Dalsgaard, J.,Dappen, W., Dziembowski, W., Gough,D., and Thompson, M.: “Sources ofUncertainty in Direct SeismologicalMeasurements of the Solar HeliumAbundance”

Kotov, V.A., Haneychuk, V.I., and Tsap,T.T.: “Seismic Evidence for a RapidlyRotating Solar Core”

LaBonte, B.J., and Ryutova, M.: “A Possi-ble Mechanism for Enhanced Absorptionof p-Modes in Sunspot and PlageRegions”

Lazrek, M., and Hill, F., “TemporalWindow Effects and Their Deconvolu-tion from Solar Oscillation Spectra”

Monteiro, M.J.P.F.G., Christensen-Dals-gaard, J., and Thompson, M.J.:“Detecting Convective Overshoot inSolar-Type Stars”

Moskalik, P., and Dziembowski, W.A.:“New Opacities and the Origin of the βCephei Pulsations”

Ronan, R.S., and LaBonte, B.J.:“Intermediate Degree p-Mode FrequencySplittings Near Solar Maximum”

Rossi, P., Kalkofen, W., Bodo, G., andMassaglia, S.: “Oscillations in aStratified Atmosphere”

Schou, J., Christensen-Dalsgaard, J., andThompson, M.J.: “Two-DimensionalHelioseismic Inversions”

Shou, J., Brown, T. M., and Bachmann, K.T.: “Preliminary Results from Observa-tions with the Fourier Tachometer”

Toner, C.G., and Jefferies, S.M.: “AccurateMeasurement of the Geometry for aFull-Disk Solar Image and Estimation ofthe Observational Point Spread Func-tion”

Uitenbroeck, H, and Bruls, J.: TheFormation of Helioseismology Lines.III: Partial Redistribution Effects inWeak Solar Resonance Linens.

Wilson, P.R.: “Helioseismology Data andthe Solar Dynamo”

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Graduate StudentResearch Fellowship

The National Solar Observatory(NSO) has a research opportunity fora graduate student in the field of

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helioseismology. This position is insupport of the NASA/Stanford SolarOscillations Investigation ( SOI ) pro-ject, but the successful candidate willreside in Tucson. Applicants must becurrently enrolled, in good standing, ina doctoral graduate program at an ac-credited university, must have anofficial thesis advisor, and must havecompleted all course work and passedany necessary qualifying examinationsat their university.

The research topic must also be ap-proved by the candidate’s thesis com-mittee. The topic should be in the areaof observational helioseismology, pre-ferably using moderately high-resolution images similar to those thatwill be obtained by the SOI experi-ment. NSO will soon begin operatingthe High-Degree Helioseismometer(HDH) at the Kitt Peak Vacuum Tele-scope. This instrument will obtain1024 × 1024 full-disk Ca K intensitysolar images, which provide a usefulproxy for the SOI data. Possible re-search topics include the developmentof techniques to measure the parame-ters of high-degree oscillations, thedevelopment of four-dimensionalFourier transform techniques to studywave propagation in the solar atmo-sphere, and the theoretical and obser-vational study of wave trapping in su-pergranules.

The research advisor at NSO will beFrank Hill, the Global Oscillation Net-work Group (GONG) Data Scientist.Applications should be sent to

Revell RaynePersonnel DirectorNOAOPO Box 26732Tucson, AZ 85726-6732

Applications should be received by

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November 20, 1992.

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The GONG Newsletter is a “quarterly” publication which isintended to keep the community abreast of news and pro-gress relating to the GONG project and other activitieswithin the field of helioseismology. The current mailing listfor the Newsletter includes about 400 individuals whohave expressed an interest in these topics. We welcomecontributions from anyone wishing to disseminate informa-tion of general interest to this community. Contributors tothis issue include Ann Barringer, Louise Bierle, Tim Brown,Jørgen Christensen-Dalsgaard, Yvonne Ellsworth, PhilGoode, Jack Harvey, Frank Hill, Todd Hoeksema, RobHubbard, Linda Johnson, Jim Kennedy, Jim Pintar, TuckStebbins, and Roger Ulrich.

John LeibacherGONG Project Scientist, Editor

Mailing address: National Solar Observatory950 N. Cherry AvenueP.O. Box 26732Tucson, Arizona 85726-6732

Electronic Mail: Internet ≡ jleibacher@noao.eduNSI-DECnet ≡ 5355::jleibacher

Phone: (602) 325-9305

FAX: (602) 325-9278

Anyone on the GONG project staff can be reached viaelectronic mail by substituting their first initial and lastname for jleibacher in the above electronic mail ad-dresses.