13005( 7) - 25-Jun-2013 17:43:45 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13005 Version: 7 Check-in Time: 25-Jun-2013 17:43:45 STScI Edit Number: 0 Title Hubble Imaging of a Newly Discovered Main Belt Comet ------------------------------------------------------------------------------------ Type Cycle GO 20 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. David Jewitt University of California - Los Angeles Y CoI: Dr. Harold A. Weaver The Johns Hopkins University Applied Y Physics Laboratory CoI: Dr. Jessica Agarwal Max Planck Institute for Solar System N Research CoI: Dr. Stephen M. Larson University of Arizona N CoI: Mr. Max Mutchler Space Telescope Science Institute Y ------------------------------------------------------------------------------------ Abstract Main-belt comets (MBCs, or 'active asteroids') have the orbital characteristics of asteroids but also show transient, comet-like activity. Examples of mass-loss likely caused by ice sublimation and by impact have been established, while numerous additional processes are capable of launching material from asteroids. We propose two orbits of non-disruptive, target-of-opportunity observations of the next MBC discovered in order to help determine the process driving mass-loss. ------------------------------------------------------------------------------------ Observations Description ------------------------ The Main Belt Comet 133P/Elst-Pizarro has recently (mid-June 2013) erupted in activity, displaying a long, thin dust tail. Hubble observations in July or early August 2013 should help determine why this object has become active again. We plan to take WFC3/UVIS observations with the F350LP filter in two consecutive orbits to make sensitive measurements of the near-nucleus coma. Each orbit will have identical activities: images at one CCD location for the first half of the orbit and images at a dithered CCD location for the second half of the orbit. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments 13005( 7) - 25-Jun-2013 17:43:45 - [ 2] ------------------- The trigger for these observations is the discovery of an object in the main-belt having a Tisserand parameter TJ > 3.1 and showing a coma or tail. Comets have TJ < 3, asteroids have TJ > 3. The parameter is useful only in the context of the circular, restricted three-body approximation. As a result, objects with TJ very close to 3 can be either cometary or asteroidal in nature. In practice, we take TJ > 3.1 as the dividing line, since objects with larger TJ cannot be dynamically linked to the classical comets. The Tisserand constraint is quite stringent, and avoids any possibility of confusion with classical comets. 133P/Elst-Pizarro is the prototypical MBC and its recent activation is the trigger for this cycle 20 program. ------------------------------------------------------------------------------------ 13005( 7) - 25-Jun-2013 17:43:45 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: 133P-ELST-PIZARRO ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: COMET Main Belt Comet ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 TYPE=COMET, Q=2.649915931081285, E=0.1614201402748764, I=1.386923482939521, O=160.1479051307290, W=132.1299288431555, T=08-FEB-2013:20:06:43, TTimeScale=TDT, EQUINOX=J2000, EPOCH=01-AUG-2013, EpochTimeScale=TDT ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 20 +/- 2 The nucleus will be brightest in late-August 2013 (closest approach to Earth) and early September (opposition), Ephemeris Center: EARTH at which time the long exposures used here may saturate in the peak pixel. However, we prefer observing ASAP, in July or early August, in which case all the exposure times should be fine. ------------------------------------------------------------------------------------------------------------------------------------ 13005( 7) - 25-Jun-2013 17:43:45 - [ 4] Visit: 01 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 348 S (348 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 2 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 348 S (348 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 3 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 348 S (348 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 4 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 348 S (348 POS TARG 0.2, 2.41 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 5 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 348 S (348 POS TARG 0.2, 2.41 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 6 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 252 S (252 POS TARG 0.2, 2.41 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 133P-ELST-PIZARRO 1 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 133P-ELST-PIZARRO 2 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 133P-ELST-PIZARRO 3 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 133P-ELST-PIZARRO 4 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 133P-ELST-PIZARRO 5 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 133P-ELST-PIZARRO 6 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 13005( 7) - 25-Jun-2013 17:43:45 - [ 5] Visit: 02 Visit Requirements: AFTER 01 BY 0.9 Orbits TO 1.5 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 348 S (348 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 2 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 348 S (348 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 3 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 348 S (348 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 4 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 348 S (348 POS TARG 0.2, 2.41 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 5 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 348 S (348 POS TARG 0.2, 2.41 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 6 133P-ELST-P WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 1 252 S (252 POS TARG 0.2, 2.41 IZARRO S S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 133P-ELST-PIZARRO 1 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 133P-ELST-PIZARRO 2 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 133P-ELST-PIZARRO 3 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 133P-ELST-PIZARRO 4 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 133P-ELST-PIZARRO 5 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 133P-ELST-PIZARRO 6 WFC3/UVI ACCUM UVIS2 F350LP none none none none 1 N/A S 13005( 7) - 25-Jun-2013 17:43:45 - [ 6] Summary Form for Proposal 13005 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 0.9 Orbits TO 1.5 Orbits, POS TARG 0.2, 2.41 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F350LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names 133P-ELST-PIZARRO ------------------------------------------------------------------------------------------------------------------------------------