0Assigned ID: 2628
----- Attempting Submission 1 (Fri Oct 01 21:10:57 GMT 2021) -----
HST Phase I Proposal 2628 successfully submitted.
Receipt: # 2628-1Update 1: Relaxed time requirement of first visit.
Update 2: Enable gyro bias update for visits 00, 10, 20. Update exposure time accordingly.234600358----- Attempting Submission 1 (Fri Oct 08 13:33:20 GMT 2021) -----
HST Phase II Proposal 16852 successfully submitted.
Receipt: # 16852-1
----- Attempting Submission 2 (Fri Oct 08 13:52:18 GMT 2021) -----
----- Attempting Submission 3 (Fri Oct 08 15:49:37 GMT 2021) -----Characterizing the aftermath of mega-outbursts of Centaur 29PWe request 6 orbits of observing time to investigate the aftermath of a 7 magnitude series of outbursts of centaur 29P/Schwassmann-Wachmann using WFC3/UVIS. At 5.5 au from the Sun, this object is known for its irregular activity. The series of outbursts that started this week (9/27) are the largest on record, making the object brighter than ever before. The event provides a unique opportunity to study material ejected from below the surface and to investigate what processes drive these large outbursts. The versatility of WFC3 is necessary to search for fragments, characterize the morphology and amount of the ejected material, and use narrow and medium band filters to evaluate dust color and content. We request three 2-orbit visits to characterize the ejecta around 29P and to perform a deep search for 100 meter diameter fragments. We will determine the dynamical and color evolution of the ejecta to constrain the kinematics and thus the possible mechanisms of the outbursts. Only HST is capable of capturing the high spatial resolution images necessary to capture faint fragments near the active 29P nucleus to investigate the outbursts and their source.The objectives of the proposal are to characterize morphology and color of the outburst ejecta around 29P and to perform a deep search of any large fragments. Because the outburst ejecta is expanding and darkening, we would like the observations to be scheduled as soon as possible.
We plan to organize the 6 orbits into 3 2-orbit visits separated by about 1 week. In each visit, the two orbits should be executed back to back in order to facilitate the color analysis and stacking of images to increase the SNR. Because we only require two consecutive orbits in each visit, and we do not require extreme pointing accuracy with the use of 160" full field of view UVIS, we can disable the gyro bias update for all orbits to gain 5-6 min of extra exposure time in each orbit.
Each orbit will consist of 5 full-frame exposures for the largest possible spatial coverage of the ejecta. Each orbit will have two F350LP exposures, one F487N exposure, and two exposures with F689M for one orbit and F845M for the other. We use a two-point dither pattern in each orbit to dither across the chip gap and bad pixels/columns for all filters. In order to avoid the main part of the coma from falling into the chip gap, we will use POSTARG parameters to put the nucleus at 20" from the gap on the opposite chips in the two dither points. The dither will also offset the nucleus by 3" horizontally (along the gap direction).
The exposure times are estimated based on the previous observations of 29P with the same instrument and filters. The F689M, F845M, and F487N filters will not saturate the nucleus. The F350LP exposures will saturate the core of the comet in order to perform a deep search for faint fragments around the nucleus. With one 550 s exposures in F350LP filter, we expect to reach a magnitude just over 27 for SNR=5.
The 3-sigma position uncertainty of 29P is about 0.05" based on JPL Horizons, i.e., about 1 UVIS pixel, which brings no concerns for the pointing accuracy requirement. No orientation requirement is needed for our observations.The team has extensive experience with small body observations with HST and consists of expert observers, modelers, and data analysts, who have developed sophisticated techniques for measuring and interpreting comet activity and composition. All team members will aid in integrating the results from the different instruments and will be involved in the preparation of scientific publications.
The PI and team leader Dennis Bodewits (Auburn U.) is an expert on comet activity and coma physics and brings experience with the Rosetta and EPOXI comet missions. He has led several comet observing campaigns for several orbiting telescopes, including comet observations with HST, Chandra, XMM-Newton, and the Neil Gehrels-Swift Observatory. He led the HST/COS observations of interstellar comet 2I/Borisov that resulted in the discovery that it was highly enriched in CO. Alan Stern (SWRI) and John Noonan (U. Arizona/LPL) were, respectively the Rosetta Alice PI and one of the science team members; Both are experts in the analysis of cometary Far-Ultraviolet observations and have used HST in the past to make such studies. Stern also is the PI of the New Horizons mission to Pluto and Arrokoth and therefore an expert in Kuiper Belt Objects; as a Centaur SW1 is an escaped KBO. Maria Womack (U. Central Florida) is an expert on the distant activity of Centaurs and comets. Walt Harris (U. Arizona/LPL) specializes in Far Ultraviolet spectroscopy and the development of instrumentation for ground, suborbital, and space based remote sensing. Jian-Yang Li (Planetary Science Inst.) is an expert comet observer who has successfully led and/or participated in over 20 HST programs. Michael S.P. Kelley (U. Maryland) is an expert dust modeler who leads the comet outburst detection and follow-up programs on the Zwicky Transient Facility. Tony Farnham (U. Maryland) is an expert on rotational studies of comets and is using the TESS datasets to study temporal phenomena (including periodic variability and outbursts) of dozens of comets.Solar System Astronomy0falseSUPPORTEDSOLAR SYSTEMYESCOMETComet29PTYPE=COMET,Q=5.73285105168272,E=0.04410336970518595,I=9.37985821466569
,O=312.5786146183075,W=50.41602027596368,T=07-APR-2019:01:07:11,TTimeScale=TDB,EQUINOX=J2000,EPOCH=31-JAN-2012:00:00:00,EpochTimeScale=TDBEARTHWFC3/UVISImagingNoNoF350LPWFC3/UVISImagingNoNoF487NWFC3/UVISImagingNoNoF689MWFC3/UVISImagingNoNoF845MUsing ephemeris for target 16852-01-29P-SW1ephemeris data for target 16852-01-29P-SW1 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 21.152 to 23.089. ephemeris interval: 21.273 to 23.274Timing link suitability includes constraints ([02 After 01 by 0.1 to 0.1 days])The scheduling data was generated by CASM 29.2.CASM was run in Phase II mode./System/Volumes/Data/solaris/user1/sherwin/16852/OP-cache/16852-v01.xml1635263455000253.1556055838592(Tic-Visit
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)false10Using ephemeris for target 16852-02-29P-SW1ephemeris data for target 16852-02-29P-SW1 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 21.152 to 23.089. ephemeris interval: 21.273 to 23.274Timing link suitability includes constraints ([02 After 01 by 0.1 to 0.1 days] [10 After 02 by 6.5 to 7.5 days])The scheduling data was generated by CASM 29.2.CASM was run in Phase II mode./System/Volumes/Data/solaris/user1/sherwin/16852/OP-cache/16852-v02.xml1635269171000253.12785773999434(Tic-Visit
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)true10Using ephemeris for target 16852-10-29P-SW1ephemeris data for target 16852-10-29P-SW1 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 21.152 to 23.089. ephemeris interval: 21.273 to 23.274Timing link suitability includes constraints ([10 After 02 by 6.5 to 7.5 days] [11 After 10 by 0.1 to 0.1 days])The scheduling data was generated by CASM 29.2.CASM was run in Phase II mode./System/Volumes/Data/solaris/user1/sherwin/16852/OP-cache/16852-v10.xml1637676989000223.44333275266848(Tic-Visit
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)true10Using ephemeris for target 16852-11-29P-SW1ephemeris data for target 16852-11-29P-SW1 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 21.152 to 23.089. ephemeris interval: 21.273 to 23.274Timing link suitability includes constraints ([11 After 10 by 0.1 to 0.1 days] [20 After 11 by 6.5 to 7.5 days])The scheduling data was generated by CASM 29.2.CASM was run in Phase II mode./System/Volumes/Data/solaris/user1/sherwin/16852/OP-cache/16852-v11.xml1637682707000221.94196884858974(Tic-Visit
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)true10Using ephemeris for target 16852-20-29P-SW1ephemeris data for target 16852-20-29P-SW1 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 21.152 to 23.089. ephemeris interval: 21.273 to 23.274Timing link suitability includes constraints ([20 After 11 by 6.5 to 7.5 days] [21 After 20 by 0.1 to 0.1 days])The scheduling data was generated by CASM 29.2.CASM was run in Phase II mode./System/Volumes/Data/solaris/user1/sherwin/16852/OP-cache/16852-v20.xml(Tic-Visit
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