OBSERVING SATURN WITH THE · PDF fileOBSERVING SATURN WITH THE ALPO Julius ... •...
Transcript of OBSERVING SATURN WITH THE · PDF fileOBSERVING SATURN WITH THE ALPO Julius ... •...
OBSERVING SATURN WITH THE ALPOOBSERVING SATURN WITH THE ALPOOBSERVING SATURN WITH THE ALPOOBSERVING SATURN WITH THE ALPO
Julius L. Benton, Jr.Coordinator
ALPO Saturn Section
July 25, 2015 ALPO Saturn Section 1
E-Mail: [email protected]
Website: http://www.alpo-astronomy.org
Saturn e-Group: http://tech.groups.yahoo.com/group/Saturn-ALPO
This presentation and its contents is intended solely for the purpose of exhibiting observational activities and programs organized and conducted by the ALPO Saturn Section and its associates. The data, images and other information contained herein shall not be reproduced, used or distributed, in whole or in part, without expressed written authorization of the ALPO Saturn Section.
July 25, 2015 ALPO Saturn Section 2
Guiding Principle of the ALPOGuiding Principle of the ALPOGuiding Principle of the ALPOGuiding Principle of the ALPO
Encourage and coordinate regular, systematic
investigations of our solar system with
instrumentation readily available to amateur
astronomers.
July 25, 2015 ALPO Saturn Section 4
Value of Amateur Planetary ObservationsValue of Amateur Planetary ObservationsValue of Amateur Planetary ObservationsValue of Amateur Planetary Observations
• Freedom to observe at leisure for extended periods of time.
• Systematic observations provide long-term records for further
study by professional astronomers.
• Observations of changing atmospheric features on Saturn are
used to alert professionals in selecting targets for high-
resolution spacecraft imaging.
• Skilled observers routinely produce excellent digital images at
different wavelengths that are useful to professional
astronomers.
• Amateurs have actively participated in the Cassini mission.
July 25, 2015 ALPO Saturn Section 5
Some Achievements by Amateur ObserversSome Achievements by Amateur ObserversSome Achievements by Amateur ObserversSome Achievements by Amateur Observers
• Long-term visual work confirmed that distinct belts and zones are
not just occasionally seen on Saturn’s globe.
• Cassini's and Encke's divisions are not the only “gaps” in the rings
(ripples or “intensity minima” were routinely seen prior to Voyager).
• Ring C can be seen and imaged with small-to-moderate apertures.
• Long-term studies show a recurring pattern for atmospheric storms.
• CM data reveal variations in rotation rates for the SEB and NEB.
• Intensity estimates of belts and zones show a subtle seasonal effect.
• The tenuous Ring E external to Ring A was seen prior to Voyager.
• Dusky radial "spokes" were reported in Ring B prior to Voyager.
• The bicolored aspect of the rings and brightness asymmetries around
Ring A have been seen visually and successfully imaged.
July 25, 2015 ALPO Saturn Section 6
Suggested Suggested Suggested Suggested Equipment for Equipment for Equipment for Equipment for Observing SaturnObserving SaturnObserving SaturnObserving Saturn
• Minimum aperture recommendations:
� 10.2 cm ( 4.0 in ) for refractors.
� 15.2 cm (6.0 in) for Newtonians and Catadioptrics.
• Equatorial mount with slow-motion controls and a clock-drive.
• Color filters of known wavelength transmission.
• A printed or on-line ephemeris (e.g., Astronomical Almanac,
WinJupos, WIMP).
• Digital imager and a laptop with software to process images.
July 25, 2015 ALPO Saturn Section 7
• Saturn apparitions last about 378 days between conjunctions.
� Plan your observations well ahead of the observing season.
� Start observing early when Saturn is just visible before sunrise.
� Continue monitoring Saturn through opposition to conjunction.
� Keep accurate records (e.g. date & time, location, telescope, magnifications,
filters, etc.).
• Use standard observing forms for reporting data (available on
ALPO Website).
• Submit all observations on a regular basis via e-mail or s-mail).
• Strive for simultaneous observations (i.e., two or more
observers viewing at the same time on the same date).
Some Keys Some Keys Some Keys Some Keys to Meaningful Resultsto Meaningful Resultsto Meaningful Resultsto Meaningful Results
July 25, 2015 ALPO Saturn Section 8
ALPO Saturn Observing ProgramsALPO Saturn Observing ProgramsALPO Saturn Observing ProgramsALPO Saturn Observing Programs• Visual numerical relative intensity estimates.
• Full-disc drawings of Saturn using ALPO observing blanks.
• Regular digital imaging of Saturn at various wavelengths.
• Central meridian (CM) transit timings of features on the globe.
• Visual estimates and measurements of belt and zone latitudes.
• Visual monitoring and imaging of "intensity minima“ in the rings.
• Studies of the bicolored aspect and brightness asymmetries around
the circumference of Ring A.
• Accurate timing and imaging of stellar occultations by Saturn.
• Specialized studies at small or edgewise ring inclinations (e.g.,
transits of satellites and their shadows across the globe).
• Visual observations and magnitude estimates of Saturn’s satellites.
July 25, 2015 ALPO Saturn Section 9
Sample ALPO Sample ALPO Sample ALPO Sample ALPO
Saturn Drawing Saturn Drawing Saturn Drawing Saturn Drawing
BlankBlankBlankBlank
Although regular digital imaging of
Saturn is very important, observers
should not neglect to make routine
visual numerical relative intensity
estimates of globe and ring
features.
July 25, 2015 ALPO Saturn Section 10
Saturn’s Changing Ring Tilt Since 2009Saturn’s Changing Ring Tilt Since 2009Saturn’s Changing Ring Tilt Since 2009Saturn’s Changing Ring Tilt Since 2009
• Saturn’s rings attain a maximum tilt of +27o toward Earth in October 2017.
• Summer solstice is approaching in Saturn’s Northern Hemisphere.
• Next edgewise ring presentations occur in 2025 (unfavorable) and 2039.
July 25, 2015ALPO Saturn Section11
Standard Nomenclature for SaturnStandard Nomenclature for SaturnStandard Nomenclature for SaturnStandard Nomenclature for Saturn
July 25, 2015 ALPO Saturn Section 12
• Conjunction 2014 Nov 18d UT
• Opposition 2015 May 23d
• Conjunction 2015 Nov 30d
Opposition Data
Equatorial Diameter Globe 18.5″
Polar Diameter Globe 16.5″
Major Axis of Rings 41.9″
Minor Axis of Rings 17.2″
Visual Magnitude (mv) +0.0mv
B = +24.2o
Declination −18.3o
Geocentric Phenomena for 2014Geocentric Phenomena for 2014Geocentric Phenomena for 2014Geocentric Phenomena for 2014----15 Apparition15 Apparition15 Apparition15 Apparition
July 25, 2015 ALPO Saturn Section 13
SOME INTERESTING PASTSOME INTERESTING PASTSOME INTERESTING PASTSOME INTERESTING PASTAND AND AND AND
RECENT OBSERVATIONSRECENT OBSERVATIONSRECENT OBSERVATIONSRECENT OBSERVATIONS
July 25, 2015 ALPO Saturn Section 14
• First imaged by Cassini at 23:26UT on December 5, 2010 at 35°N
Saturnigraphic latitude.
• By late February 2011 the massive storm widened by 15,000km
encircling the globe between Saturnigraphic latitude 35°N and 40°N.
• White spots arise as columns of material break through the upper
NH4-ice cloud deck and spread out.
• The NTrZ storm illustrates how shifting seasons and insolation can
help stir up weather on Saturn.
Images courtesy of NASA‘s Cassini Mission
The Memorable Great White Storm of 2010The Memorable Great White Storm of 2010The Memorable Great White Storm of 2010The Memorable Great White Storm of 2010----11111111
July 25, 2015 ALPO Saturn Section 15
The Memorable Great White Storm of 2010The Memorable Great White Storm of 2010The Memorable Great White Storm of 2010The Memorable Great White Storm of 2010----11111111• ALPO Saturn Section received an appeal from Cassini scientists to
provide as many images of the NTrZ white spot as possible.
• Amateurs responded as early as December 10, 2010 and Pro-Am
cooperation continued during the 2010-11 apparition and beyond.
S
E W
N
(IAU)
July 25, 2015 ALPO Saturn Section 16
Lingering NTrZ Storm Remnants in 2012 & 2013Lingering NTrZ Storm Remnants in 2012 & 2013Lingering NTrZ Storm Remnants in 2012 & 2013Lingering NTrZ Storm Remnants in 2012 & 2013
• Between Saturnigraphic latitude 40oN and 45oN the globe remained
morphologically complex and brighter than usual following the storm.
2012201220122012
2013201320132013
S
E W
N
(IAU)
July 25, 2015 ALPO Saturn Section 17
SATURN OBSERVATIONS DURING SATURN OBSERVATIONS DURING SATURN OBSERVATIONS DURING SATURN OBSERVATIONS DURING THE CURRENT 2014THE CURRENT 2014THE CURRENT 2014THE CURRENT 2014----15 APPARITION15 APPARITION15 APPARITION15 APPARITION
July 25, 2015 ALPO Saturn Section 18
PrePrePrePre----Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014----15151515
S
E W
N
(IAU)
Shadow of the
Globe on the Rings
is toward the East (IAU)
prior to Opposition
NNNTeZ Dark OvalNTrZ White Spot
North Polar Hexigon
NNNTeZ Dark Oval
July 25, 2015 ALPO Saturn Section 19
PrePrePrePre----Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014----15151515
S
E W
N
(IAU)
Shadow of the
Globe on the Rings
is toward the East (IAU)
prior to OppositionBright area in EZn Elongated EZn White area
July 25, 2015 ALPO Saturn Section 20
Saturn at Opposition in 2014Saturn at Opposition in 2014Saturn at Opposition in 2014Saturn at Opposition in 2014----15151515S
E W
N
(IAU)
• The Seeliger Opposition Effect is an apparent brightening of the rings
for a short interval near opposition.
• Caused by coherent back-scattering of µ-sized icy particles in the rings
when the phase angle between Sun-Saturn-Earth is <0.3°.
2014201420142014----15 15 15 15 Opposition DataOpposition DataOpposition DataOpposition Data::::
2015 May 23d UT
Eq Dia Globe = 18.5”
Po Dia Globe = 16.5”
Maj Axis Rings = 41.9”
Min Axis Rings = 17.2”
Visual Mag = 0.0
B = +24.2o
Declination = −18.3o
July 25, 2015 ALPO Saturn Section 21
Changing Position of the Shadow of the Globe Changing Position of the Shadow of the Globe Changing Position of the Shadow of the Globe Changing Position of the Shadow of the Globe
on the Rings Before and After Oppositionon the Rings Before and After Oppositionon the Rings Before and After Oppositionon the Rings Before and After Opposition
S
E W
N
(IAU)
Sh G on R
Prior to OppositionPrior to OppositionPrior to OppositionPrior to Opposition: : : :
ShShShSh G on R is to the IAU EastG on R is to the IAU EastG on R is to the IAU EastG on R is to the IAU East
At OppositionAt OppositionAt OppositionAt Opposition: : : :
ShShShSh G on R is behind GlobeG on R is behind GlobeG on R is behind GlobeG on R is behind Globe
After OppositionAfter OppositionAfter OppositionAfter Opposition: : : :
ShShShSh G on R is to the IAU WestG on R is to the IAU WestG on R is to the IAU WestG on R is to the IAU West
Sh G on R
Images courtesy of Christopher Go of Cebu City, Philippines
July 25, 2015 ALPO Saturn Section 22
PostPostPostPost----Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014----15151515
S
E W
N
(IAU)
Shadow of the
Globe on the Rings
is toward the West (IAU)
after to Opposition
NNNTeZ Dark Oval
Multiple small NTrZ White Spots
July 25, 2015 ALPO Saturn Section 23
PostPostPostPost----Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014Opposition Views of Saturn in 2014----15151515
S
E W
N
(IAU)
Shadow of the
Globe on the Rings
is toward the West (IAU)
after to OppositionNNNTeZ Dark Oval and surrounding elongated bright “collar”
EZn White Spot
NNNTeZ Dark Oval and surrounding elongated bright “collar”
EZn White Spot
EZs White Spot
July 25, 2015 ALPO Saturn Section 24
Highlights of the 2014Highlights of the 2014Highlights of the 2014Highlights of the 2014----15 Apparition (So Far)15 Apparition (So Far)15 Apparition (So Far)15 Apparition (So Far)• The rings are inclined by +24o in 2014-15, so near-optimum views are
possible of Saturn’s Northern Hemisphere and North face of the rings.
• Numerous “intensity minima” have been seen and imaged in Ring B.
• The Pro-Am effort that began back in 2004 when Cassini started
monitoring Saturn at close range is still active in 2014-15.
• Observers are reporting discrete features within the belts and zones:
� Recurring dark spots have been imaged at +41o and +64o Saturnigraphic
latitude that seem to be increasing in complexity (especially the one at +64o).
� A recurring bright feature in the EZn has been imaged since about June 20th.
� Based on intensity estimates, the EZn is slightly brighter than usual.
� Multiple small bright spots have been imaged in the NTrZ (possible remnants of
the 2010-11 storm?).
• Despite Saturn’s more southerly declination of -18o observations are approaching near-record numbers in 2014-15.
July 25, 2015 ALPO Saturn Section 25
Saturn and How to Observe It
is a comprehensive guide to
ALPO Saturn observing
programs and techniques.
A fully revised edition is
expected to be published by
mid-2016.
This presentation and its contents is intended solely for the purpose of exhibiting observational activities and programs organized and conducted by the ALPO Saturn Section and its associates. The data, images and other information contained herein shall not be reproduced, used or distributed, in whole or in part, without expressed written authorization of the ALPO Saturn Section.
More About Observing SaturnMore About Observing SaturnMore About Observing SaturnMore About Observing Saturn