12792( 5) - 28-Dec-2011 14:02:50 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12792 Version: 5 Check-in Time: 28-Dec-2011 14:02:50 STScI Edit Number: 3 Title High Spatial Resolution Photometric Imaging of the Area Around the Nucleus of C/2011 W3 Lovejoy ------------------------------------------------------------------------------------ Type Cycle GO/DD 19 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Matthew M Knight Lowell Observatory CoI: Dr. Harold A. Weaver The Johns Hopkins University Applied Y Physics Laboratory CoI: Dr. Carey M Lisse The Johns Hopkins University Applied N Physics Laboratory CoI: Dr. Neil Dello Russo The Johns Hopkins University Applied N Physics Laboratory CoI: Dr. Steven Chesley Jet Propulsion Laboratory N ------------------------------------------------------------------------------------ Abstract We propose to observe the newly discovered comet C/2011 W3 Lovejoy at one epoch near its closest approach to the Earth in early-January 2012. Lovejoy is a member of the Kreutz group of sungrazing comets and is the first sungrazing comet known to have survived perihelion during the era of modern observations (since 1970). Its size is currently unconstrained but is critical for understanding Lovejoy?s place in the Kreutz group hierarchy (either as one of the 1600+ known ?pygmy? fragments or one of a handful of major fragments of the parent body, which support and fuel the rest). Kreutz comets are known to fragment frequently, and we expect that Hubble?s high spatial resolution will reveal individual fragments undetectable by any other means. We will estimate the size distribution of these fragments. Due to Lovejoy?s extreme southern declination, small solar elongation, and 300+ year orbit, these observations can only be obtained using Hubble, and cannot be accomplished at any other epoch. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will obtain 6 x 350s exposures using the F606W filter. We will use two different dither positions (3 images at each dither location) to fill-in the gap between the two CCDs and to mitigate the effects of bad pixels. If necessary, the exposure time for the sixth image should be reduced to fit the observations into one orbit. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments 12792( 5) - 28-Dec-2011 14:02:50 - [ 2] ------------------- ------------------------------------------------------------------------------------ 12792( 5) - 28-Dec-2011 14:02:50 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: LOVEJOY ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: COMET Newly discovered sungrazing comet ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 TYPE=COMET, Q=0.005554772513974684, E=0.9999271792540354, I=134.4069584659192, O=326.520935644692, W=53.61581727191412, T=16-DEC-2011:00:20:00, TTimeScale=TDB, EQUINOX=J2000, EPOCH=08-JAN-2012, EpochTimeScale=TDB ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 23 +/- 4 Ephemeris Center: EARTH Ephemeris Uncertainty: 3625 KM Acquisition Uncertainty: 10 " ------------------------------------------------------------------------------------------------------------------------------------ 12792( 5) - 28-Dec-2011 14:02:50 - [ 4] Visit: 01 Visit Requirements: DROP TO GYRO IF NECESSARY ; BETWEEN 07-JAN-2012 AND 11-JAN-2012 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 LOVEJOY WFC3/UVI ACCUM UVIS1 F606W CR-SPLIT=NO 3 350 S REQ EPHEM CORR LOVE01; S GS ACQ SCENARIO SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 2 LOVEJOY WFC3/UVI ACCUM UVIS1 F606W CR-SPLIT=NO 3 350 S POS TARG 0.2, 2.41; REQ S EPHEM CORR LOVE01 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ LOVEJOY 1 WFC3/UVI ACCUM UVIS1 F606W none none 1 none 1 N/A S LOVEJOY 1 WFC3/UVI ACCUM UVIS1 F606W none none 2 none 1 N/A S LOVEJOY 1 WFC3/UVI ACCUM UVIS1 F606W none none 3 none 1 N/A S LOVEJOY 2 WFC3/UVI ACCUM UVIS1 F606W none none 1 none 1 N/A S LOVEJOY 2 WFC3/UVI ACCUM UVIS1 F606W none none 2 none 1 N/A S LOVEJOY 2 WFC3/UVI ACCUM UVIS1 F606W none none 3 none 1 N/A S 12792( 5) - 28-Dec-2011 14:02:50 - [ 5] Summary Form for Proposal 12792 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 07-JAN-2012 AND 11-JAN-2012, DROP TO GYRO IF NECESSARY , GS ACQ SCENARIO SINGLE, POS TARG 0.2, 2.41, REQ EPHEM CORR LOVE01 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names LOVEJOY ------------------------------------------------------------------------------------------------------------------------------------