1

Ken Sembach

27-October-2005

ACS Calibration Status

ACS Websitehttp://www.stsci.edu/hst/acs

KRS 2

John BirettaRalph Bohlin

Marco ChiabergeMauro GiavaliscoShireen Gonzaga

Colin CoxLinda DresselAndy FruchterRon Gilliland

Vera Kozhurina-PlataisJesús Maíz-Apellániz

ST-ECFRichard Hook

Martin KümmelSören LarsenJeremy Walsh

Ray LucasJennifer MackMax MutchlerCheryl PavlovskyCharles ProffittAdam Riess Kailash SahuKen SembachMarco SirianniNolan Walborn

ACS Calibration Teams at STScI and ST-ECF

• This talk is an overview of ACS calibration activities. See the many talks/posters here for more details. People listed below are good sources of information.

KRS 3

ACS Status / Operation• All modes continue to operate well

• Two-gyro performance nominal

• Calibration plan for Cycle 14• STScI team has reviewed plans from previous cycles• Continuing calibrations for most previous programs (ongoing usual

calibration activities) • New programs to bring SBC calibrations up to the standard of

HRC/WFC calibrations, to better characterize the ramp filters, ultraviolet narrow-band red leak, and to estimate T-dependence of QE, CTE, and hot pixel growth

• ACS usage charted on STScI metrics page• Provides information about most frequently used modes

• http://www.stsci.edu/hst/metrics/SiUsage

KRS 4

Cycle 14 - Routine Monitoring Programs

ID # PI Title Freq.

Orbits Acc

.Notes

Ext Int

10729 Sirianni CCD Daily Monitor 4/week 0 840 … Dark, bias creation

10730 Chiaberge External CTE Monitor 6 months 9 0 1% CTE loss calibration

10732 Mutchler Internal CTE Monitor yearly 0 35 1% Check against ground

10733 Cox CCD Hot Pixel Annealing 4 weeks 0 143 … Includes monthly CTE

10734 Cox CCD Post-Flash Verification yearly 0 4 … Tracks capability only

10735 Cox SBC MAMA Recovery as needed 0 4 … After irregular safing

10736 Maiz UV Contamination Monitor 6 months 4 2 1% SBC, HRC tracking

10737 Mack CCD Stability Monitor quarterly 13 0 1%L-flat, distortion,

photometry

10738 Mack Earth Flats weekly 0 52 <1% Tracks coronagraphic spot

10739 Bohlin Internal Flat Fields 4 months 0 44 <1% SBC components once

10740 BohlinPhoto-Spectrophot. Abs.

Cal.yearly 7 0 <1% Filter throughputs, QE

Total (Cycle 14 routine monitoring programs) 33 1124

KRS 5

Cycle 14 - Special Calibration Programs

ID # PI Title Freq.Orbits

Acc. NotesExt Int

10722 Maiz SBC Geometric Distortion once 6 4 0.1 pixBasic calibration of geometric distortion

10731 Chiaberge UV Narrow-Band Red Leak once 2 0 <10% Responds to failed early cal

10741 Suchkov Continuum L-Flats - Ramps once 3 0 1% Basic calibration of flats

10742 Fruchter Ramp, Grism Wavelengths once 4 0 2% Responds to failed early cal

10743 Larsen Improved for SBC Prism once 2 2 <0.5 pix Two QSOs (1400-1800 Å)

10771 SirianniCTE & QE with Temperature

once 12 12 ASCS support test

Total (Cycle 14 special calibration programs) 29 18

KRS 6

Cycle 13 - Special Calibration Programs

ID # PI Title Freq.Orbits

Acc. NotesExt Int

10378 Biretta Polarization Calibration once 12 0 1% Last visit in July ‘05

10391 LarsenWave, Flux for Prisms

SBC+HRConce 1 11 5% Last visit in Aug ‘05

10449 Cox SBC Filter Wheel Checkout once 0 7 Use program only if needed

10450 Sirianni Functional Test MEB2 Switch once 0 2 Use program only if needed

10453 Sirianni Short Annealing Test once 0 0 Adopted for routine use

10720 RiessMonochromatic PSF in the

Redonce 1 0 Recently submitted

Total (Cycle 13 special calibration programs) 14 20

KRS 7

Cycle 14 - Calibration Orbit Summary

Cycle 14 Orbits

External Internal Outsourced*

Total Time (routine + special) 62 1142 11

With contingency 67 1253 11

* Two programs (PI = Dolphin): ACS zero point verification / Faint standard calibration

KRS 8

Recent ACS ISRs• Grism wavelength calibration

• ISR 2005-08 (Larsen & Walsh)• CCD internal flat fields

• ISR 2005-09 (Bohlin & Mack)• SBC pixel-pixel flat field

• ISR 2005-04 (Bohlin & Mack)• Astrometric improvements

• ISR 2005-06 (Koekemoer et al.)• HRC polarimetry

• ISR 2005-10 (Kozhurina-Platais & Biretta)• Two-gyro calibrations

• I. Pointing Stability (ISR 2005-07; Koekemoer et al.)• II. Coronagraphic Performance (ISR 2005-05; Cox & Biretta)

SBC flatfield

Complete list of ISRs at http://www.stsci.edu/hst/acs/documents/isrs

KRS 9

ACS High Resolution Channel

• Typically accounts for ~15-20% of ACS observing time

• Two-gyro checkout PSF shape / stability See poster by Pavlovsky

• Updated internal flat fields ISR 2005-09; Bohlin & Mack See talk by Mack

• Flats for use with polarizer filters ISR 2005-10; Kozhurina-Platais

& Biretta• PSFs and distortion corrections

ISR 2004-15; Anderson & King

(NASA, ESA, and J. Garvin (NASA/GSFC)

KRS 10

August 2005

114 exposures3 clusters

- NGC 2298 - NGC 1891 - NGC 6752

October 2005

72 exposures1 cluster (CVZ) - NGC 6752

186 ACS/HRC exposuresMin (FWHM) = 1.89Avg (FWHM) = 2.00Max (FWHM) = 2.19

ACS Instrument Performance in Two-Gyro Mode is Excellent

Three-gyro historical dataAvg (FWHM) = 2.04±0.03

PSF analayses by M. Sirianni, C. Pavlovsky, R. Lucas

KRS 11

ACS Wide Field Channel

• Typically accounts for ~75-80% of ACS observing time

• Updated internal flat fields ISR 2005-09; Bohlin & Mack

• Astrometric accuracy using GSC2 See poster by Koekemoer, also

ISR 2005-06

• Photometric stability ISR 2004-17; Riess See also talk by Mack

• PSFs and distortion corrections See talk by Anderson

NASA, ESA and The Hubble Heritage Team (STScI/AURA)

KRS 12

ACS Solar Blind Channel

• Typically accounts for ~3% of ACS observing time

More attention w/ loss of STIS• New pixel-pixel flat field available

ISR 2005-04; Bohlin & Mack• Updated darks available

ISR 2004-14; Cox• New calibrations planned

Geometric distortion correction (see poster by Maíz-Apellániz)

Prism wavelength calibration• See SBC overview poster by Cox

et al.SBC flatfield

KRS 13

ACS Coronagraphy• Typically ~3-4% of ACS observing time• Coronagraphic flat fields

ISR 2004-16; Krist

• Two-gyro coronagraphy performance ISR 2005-05; Cox & Biretta

HD 216149 2-gyro F625WHD 130948A 2-gyro F625WHD 130948A 3-gyro F625W

1.8” spot

3.0” spot

KRS 14

ACS Grism/Prism Spectroscopy• In Cycle 14

~25% of HRC observing time ~9% of WFC observing time ~23% of SBC observing time

• Slitless spectroscopy with ACS Talks by Kümmel, Meurer, and Maíz-Apellániz

• Grism spectroscopy WFC/G800L wavelength calibration (ISR 2005-08; Larsen & Walsh) WFC and HRC G800L flat field and sensitivity (ISR 2005-02; Walsh & Pirzkal)

• Prism spectroscopy Prisms used more since shutdown of STIS New wavelength/flux calibrations (see poster by Larsen)

• Software improvements aXe spectral extraction of prism/grism data (see poster by Walsh)

KRS 15

QE & CTE Temperature Dependence

• 12 orbit study to determine T-dependence of CTE, QE, hot pixel growth, etc., has relevance for

Performance of ACS in the coming years (T may increase) Future CTE temperature/time dependent corrections Aft-Shroud Cooling System considerations for SM4

• Test scheduled for November (47 Tuc, GOODS-N) fields) will obtain data at the current operating temperature and colder/hotter temperatures

WFC: -81˚, -77˚ (current), and -74˚ C HRC: -86˚, -80˚ (current), and -76˚ C

KRS 16

Charge Transfer Efficiency

Effects of poor CTE: - Signal is lost during the readout

Lower S/NDegraded detection limit

- Some trapped charge is released on short time scales, creating tails

Increased noisePSF alteration

- CTE depends on the signal level, position, background, and time

Degradation of the Charge Transfer Efficiency (CTE) is a well known problem for space-operated CCDs.

A B

Parallelreadout

Serial Readout Even if only a very small part of the charge packet is left behind in each pixel-to-pixel transfer the effect is severe:

CTE=99.99 % after 2048 transfers results in loss of ~19% of the signal

Current parallel CTE (@1620 e-) is 99.997%

Low number of transfers High number of transfers

KRS 17

WFC Parallel CTE Variation with Time

KRS 18

ACS CCD Hot Pixel Growth

WFCWFC

years

%

Hot pixels continue to increase because of radiation damageto the CCDs.

Effects of hot pixels can be reduced by dithering exposures.

Monthly anneals heal most of the hot pixels (see poster by Marco Sirianni).

KRS 19

ACS Pipeline Calibrations (see talk by Max Mutchler)

• Most recent ACS pipeline improvements

• Emphasis on bias and dark calibrations, including hot pixels

• Reference file production and delivery

• Data quality flagging and monitoring

• Ramifications for downstream data reductions, e.g. drizzling

WFC Dark

WFC Bias

KRS 20

Automated ACS Bias and Dark Reference File Production, and Improved Detector Trend Analysis

Ray A. Lucas (STScI), Mike Swam (STScI), Max Mutchler (STScI), and Marco Siriarnni (ESA/STScI)

Automatic TriggeringBased on HST Schedule

Automated Retrieval ofRaw Data From STScI Data Archive

Automated Processing toMake Reference Biases and Darks from Raw Data

Automatic Copy of Daily Darks andStatistics to Storage Disk for Long- Term Trend Analysis

Files Delivered to OPUS and Archive For Use in Pipeline and OTFC

Users

KRS 21

ACS Documentation• Cycle 15 Instrument Handbook streamlining and updates

• Length reduced by ~15% (310 pages trimmed to 262) w/o loss of content• Some calibration plan reference material moved to ACS website• Indexing update to make information easier to access in both paper and electronic

versions of handbook • Released with Cycle 15 Call for Proposals

• Cycle 15 Data Handbook update planned• Minor updates to wording in various places and syntax in examples

KRS 22

ACS Press Releases(Comets, Planets, and Stars) Comet 9P/Tempel 1

Before and After Deep Impact

Debris Ring Reshaped By Planet Around Nearby Star

Hubble Makes Movie of Neptune's Dynamic Atmosphere

Hubble Tracks Ceres

ACS Press Releases(Black Holes and Supernovae)

Hubble Pinpoints Doomed Supernova Progenitor

Black Hole in Search of a Home

ACS Press Releases(Nebulae and Galaxies)

Hubble Spies a Zoo of Galaxies

Scattered Light from the Boomerang Nebula"Big Baby" Galaxies in the Newborn Universe

Hubble/Chandra Image SNR N132D in the LMC