13197( 2) - 02-Apr-2013 20:58:08 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13197 Version: 2 Check-in Time: 02-Apr-2013 20:58:08 STScI Edit Number: 0 Title Distant Activity of Comet ISON ------------------------------------------------------------------------------------ Type Cycle GO/DD 20 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Michael F. A'Hearn University of Maryland Y CoI: Dr. Dennis Bodewits University of Maryland N CoI: Dr. Paul D. Feldman The Johns Hopkins University N CoI: Dr. Harold A. Weaver The Johns Hopkins University Applied N Physics Laboratory CoI: Tony L. Farnham University of Maryland N CoI: Dr. Lori M. Feaga University of Maryland N CoI: Dr. Matthew M Knight Lowell Observatory N ------------------------------------------------------------------------------------ Abstract We propose to obtain spectra of the newly discovered, sun-grazing comet ISON (C/2012 S1) well before it reaches the heliocentric distance at which water-sublimation would dominate the activity, i.e. r>3 AU. The comet is clearly active beyond 5 AU and understanding which volatiles are driving the activity is a key question that must be answered before the physical processes change with the onset of rapid water sublimation. ------------------------------------------------------------------------------------ Observations Description ------------------------ We request 4 orbits using COS/G160M to provide a sensitive search for CO (via the 4PG emissions). If Q is ~10^28, the CO emission can be detected in a single orbit. Observing in 4 different orbits will allow us to determine the temporal variability in the comet's activity if it is roughly 10^28 s^-1. Otherwise we plan to co-add the data from all four orbits to place even stricter constraints, at the level of several 10^27 s-1, on the CO production rate. COS/NUV ACQ/SEARCH and ACQ/IMAGE will be used in each COS orbit to accurately place the nucleus in the aperture (PSA), a technique that worked beautifully during our previous comet observations. We also request 1 orbit using STIS/G230L with the 2'' slit to search for OH emission, from which we can determine the H2O production rate. Using a vectorial model for the OH spatial distribution (Festou, A&A, v95, p69, 1981) and the sensitivity of STIS/G230L based on our previous cometary observations, we estimate the OH emission could be detected with S/N ~ 5 in a single orbit if QH2O ~ 10^29. Although such a high H2O production rate from the nucleus is not expected, a cloud of icy grains might surround C/ISON, and the sublimation of those grains could dramatically raise the amount of H2O in the coma. Our observations with STIS/G230L could test this hypothesis. The STIS/G230L observations will also cover emissions from CS, S2, and the forbidden Cameron bands of CO (from which the CO2 production rate can be derived; see Weaver et al., ApJ, v422, p374, 1994), although the chances of detecting these emissions are slim. STIS/CCD ACQ will be used in each STIS orbit to accurately center the 13197( 2) - 02-Apr-2013 20:58:08 - [ 2] nucleus in the slit, and this has worked well during previous comet observations. We also plan to take one STIS/CCD F28x50LP full-frame image at the back end of the STIS/G230L orbit to provide context for our spectroscopic program (e.g., to provide information on jets and other coma asymmetries). Given its large heliocentric and geocentric distances, the comet's apparent motion is relatively slow (~18"/hr) and is easily within HST's tracking capabilities. We have requested that the STIS orbit be the middle of the five orbits, all of which are optimized if they are sequential. This placement maximizes the chance of seeing variability in the CO outgassing if it is significant and provides our context image at the midpoint of the observations Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- Ephemeris updates will be required ------------------------------------------------------------------------------------ 13197( 2) - 02-Apr-2013 20:58:08 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: ISON ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: COMET Comet ISON (C/2012 S1) ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 TYPE=COMET, Q=0.01250228833615271, E=1.000004178571949, I=61.86120174134099, O=295.7371915514632, W=345.5093083227027, T=28-NOV-2013:18:42:10, TTimeScale=TDT, EQUINOX=J2000, EPOCH=08-JAN-2013, EpochTimeScale=TDT ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 16.5 +/- 2.0 V-mags are for the nucleus. Ephemeris offsets will be uplinked, if necessary, to correct Ephemeris Center: EARTH for any errors in the JPL #20 solution. Ephemeris Uncertainty: 15000 KM Acquisition Uncertainty: 5 " MOSS Planning Start: Tue Apr 02 00:00:00 GMT 2013 MOSS Planning End: Fri May 10 00:00:00 GMT 2013 MOSS Show Windows: true ------------------------------------------------------------------------------------------------------------------------------------ 13197( 2) - 02-Apr-2013 20:58:08 - [ 4] Visit: 01 Visit Requirements: SEQ 01, 02, 03, 04, 05 WITHIN 6 Orbits On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ISON COS/NUV ACQ/SEA PSA MIRRORA SCAN-SIZE=3 1 30 S REQ EPHEM CORR ISON01 RCH Comments: Requires ephemeris update ------------------------------------------------------------------------------------------------------------------------------------ 2 ISON COS/NUV ACQ/IMA PSA MIRRORA 1 30 S REQ EPHEM CORR ISON01 GE Comments: Requires ephemeris update ------------------------------------------------------------------------------------------------------------------------------------ 3 ISON COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=10000, FP-POS=2, 1 500 S REQ EPHEM CORR ISON01 G EXTENDED=YES see below Comments: Requires ephemeris correction ISON ------------------------------------------------------------------------------------------------------------------------------------ 4 ISON COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=10000, FP-POS=3, 1 500 S REQ EPHEM CORR ISON01 G EXTENDED=YES see below Comments: Requires ephemeris correction ISON ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ISON 1 COS/NUV ACQ/SEA PSA MIRRORA none none none none 1 N/A RCH ISON 2 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE ISON 3 COS/FUV TIME-TA PSA G160M 1589 none none none none 1 682.0 S G ISON 4 COS/FUV TIME-TA PSA G160M 1589 none none none none 1 682.0 S G 13197( 2) - 02-Apr-2013 20:58:08 - [ 5] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ISON COS/NUV ACQ/SEA PSA MIRRORA SCAN-SIZE=3 1 30 S REQ EPHEM CORR ISON02 RCH ------------------------------------------------------------------------------------------------------------------------------------ 2 ISON COS/NUV ACQ/IMA PSA MIRRORA 1 30 S REQ EPHEM CORR ISON02 GE Comments: Requires ephemeris correction ------------------------------------------------------------------------------------------------------------------------------------ 3 ISON COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=10000, FP-POS=2, 1 500 S REQ EPHEM CORR ISON02 G EXTENDED=YES see below Comments: Requires ephemeris correction ------------------------------------------------------------------------------------------------------------------------------------ 4 ISON COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=10000, FP-POS=3, 1 500 S REQ EPHEM CORR ISON02 G EXTENDED=YES see below Comments: Requires ephemeris correction ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ISON 1 COS/NUV ACQ/SEA PSA MIRRORA none none none none 1 N/A RCH ISON 2 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE ISON 3 COS/FUV TIME-TA PSA G160M 1589 none none none none 1 682.0 S G ISON 4 COS/FUV TIME-TA PSA G160M 1589 none none none none 1 682.0 S G 13197( 2) - 02-Apr-2013 20:58:08 - [ 6] Visit: 03 Visit Requirements: BEFORE 10-MAY-2013:00:00:00 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ISON STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=POINT 1 1 S REQ EPHEM CORR ISON03 Comments: requires ephemeris correction ------------------------------------------------------------------------------------------------------------------------------------ 2 ISON STIS/NUV ACCUM 52X2 G230L 2376 1 1800 S REQ EPHEM CORR ISON03 -MAMA Comments: requires ephemeris correction ------------------------------------------------------------------------------------------------------------------------------------ 3 ISON STIS/CCD ACCUM F28X50LP MIRROR CR-SPLIT=2, GAIN=1 1 20 S REQ EPHEM CORR ISON03 Comments: reequires ephemeris correction ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ISON 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A ISON 2 STIS/NUV ACCUM 52X2 G230L 2376 none none none none 1 N/A -MAMA ISON 3 STIS/CCD ACCUM F28X50LP MIRROR none none none 1 1 N/A ISON 3 STIS/CCD ACCUM F28X50LP MIRROR none none none 2 1 N/A 13197( 2) - 02-Apr-2013 20:58:08 - [ 7] Visit: 04 Visit Requirements: BEFORE 10-MAY-2013:00:00:00 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ISON COS/NUV ACQ/SEA PSA MIRRORA SCAN-SIZE=3 1 30 S REQ EPHEM CORR ISON04 RCH Comments: requires ephemeris correction ------------------------------------------------------------------------------------------------------------------------------------ 2 ISON COS/NUV ACQ/IMA PSA MIRRORA 1 30 S REQ EPHEM CORR ISON04 GE ------------------------------------------------------------------------------------------------------------------------------------ 3 ISON COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=10000, FP-POS=2, 1 500 S REQ EPHEM CORR ISON04 G EXTENDED=YES see below Comments: requires ephemeris update ------------------------------------------------------------------------------------------------------------------------------------ 4 ISON COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=10000, FP-POS=3, 1 500 S REQ EPHEM CORR ISON04 G EXTENDED=YES see below Comments: requires ephemeris update ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ISON 1 COS/NUV ACQ/SEA PSA MIRRORA none none none none 1 N/A RCH ISON 2 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE ISON 3 COS/FUV TIME-TA PSA G160M 1589 none none none none 1 682.0 S G ISON 4 COS/FUV TIME-TA PSA G160M 1589 none none none none 1 682.0 S G 13197( 2) - 02-Apr-2013 20:58:08 - [ 8] Visit: 05 Visit Requirements: BEFORE 10-MAY-2013:00:00:00 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ISON COS/NUV ACQ/SEA PSA MIRRORA SCAN-SIZE=3 1 30 S REQ EPHEM CORR ISON05 RCH Comments: requires ephemeris correction ------------------------------------------------------------------------------------------------------------------------------------ 2 ISON COS/NUV ACQ/IMA PSA MIRRORA 1 30 S REQ EPHEM CORR ISON05 GE ------------------------------------------------------------------------------------------------------------------------------------ 3 ISON COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=10000, FP-POS=2, 1 500 S REQ EPHEM CORR ISON05 G EXTENDED=YES see below Comments: requires ephemeris correction ------------------------------------------------------------------------------------------------------------------------------------ 4 ISON COS/FUV TIME-TA PSA G160M 1589 BUFFER-TIME=10000, FP-POS=3, 1 500 S REQ EPHEM CORR ISON05 G EXTENDED=YES see below Comments: requires ephemeris correction ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ISON 1 COS/NUV ACQ/SEA PSA MIRRORA none none none none 1 N/A RCH ISON 2 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE ISON 3 COS/FUV TIME-TA PSA G160M 1589 none none none none 1 682.0 S G ISON 4 COS/FUV TIME-TA PSA G160M 1589 none none none none 1 682.0 S G 13197( 2) - 02-Apr-2013 20:58:08 - [ 9] Summary Form for Proposal 13197 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X2, F28X50LP, PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV, STIS/CCD, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ, ACQ/IMAGE, ACQ/SEARCH, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT, BUFFER-TIME=10000, CR-SPLIT=2, EXTENDED=YES, FP-POS=2, FP-POS=3, GAIN=1, SCAN-SIZE=3 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BEFORE 10-MAY-2013:00:00:00, REQ EPHEM CORR ISON01, REQ EPHEM CORR ISON02, REQ EPHEM CORR ISON03, REQ EPHEM CORR ISON04, REQ EPHEM CORR ISON05, SEQ 01, 02, 03, 04, 05 WITHIN 6 Orbits ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G160M, G230L, MIRROR, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names ISON ------------------------------------------------------------------------------------------------------------------------------------