14524( 3) - 29-Jun-2016 16:05:38 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14524 Version: 3 Check-in Time: 29-Jun-2016 16:05:38 STScI Edit Number: 0 Title WFC3 imaging of active asteroid P/2016 G1 ------------------------------------------------------------------------------------ Type Cycle GO/DD 23 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Javier Licandro Instituto de Astrofisica de Canarias Y CoI: Noemi Pinilla-Alonso University of Central Florida N CoI: Max Mutchler Space Telescope Science Institute Y CoI: Dr. Fernando Moreno Danvila Instituto de Astrofisica de Andalucia N (IAA) CoI: Francisco Jose Pozuelos-Romero Instituto de Astrofisica de Andalucia N (IAA) ------------------------------------------------------------------------------------ Abstract We propose to observe an active main belt asteroid, P/2016 G1 (PANSTARRS), which has been observed a few days ago with the 10m Gran Telescopio CANARIAS (GTC) telescope. GTC images show that the central condensation presents a structure similar to the X-shaped one observed in P/2010 A1, which suggest that the object is breaking apart due to some unknown mechanism. Observations with the unique high resolution and sensitivity provided by HST are urgently needed to determine which mechanism is causing the disruption: a collision of asteroids, rotational mass loss, or ice sublimation. ------------------------------------------------------------------------------------ Observations Description ------------------------ We are requesting two HST orbits for deep WFC3 imaging at two epochs to determine the current state and early evolution of this unfolding asteroid disruption event. The first orbit (visit) should be scheduled as soon as possible, and the second visit should be scheduled 2-3 weeks later. In each orbit, we will obtain five long exposures (420s) using the broad F350LP filter for the greatest sensitivity in detecting faint fragments and dust. The multiple exposures will also allow us to reject cosmic rays, detector artifacts, and background star trails. We will include one dither shift to avoid missing data in the WFC3 interchip gap. The large WFC3 field-of-view (160x160 arcsec) helps to ensure that even with some possible pointing uncertainty (due to the non-gravitational forces involved in a disruption event) we can confidently place the target in the aperture. This observing strategy is identical to the one used successfully many times for previous active asteroid observations, and will add to a very uniform and high-quality collection of archival images of active asteroids with HST. The first visit for this program should be scheduled as soon as possible in a non-disruptive manner. The second visit is less urgent and can be scheduled 2-3 weeks later. A precise interval is not important. ------------------------------------------------------------------------------------ 14524( 3) - 29-Jun-2016 16:05:38 - [ 2] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: P2016-G1 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID Active Asteroid or Main Belt Comet ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 TYPE=COMET, Q=2.040661899407874, E=.2100254027633657, I=10.967920669499, O=204.0747464141863, W=111.2801773466586, T=26-JAN-2017:05:23:25, TTimeScale=UTC, EQUINOX=J2000, EPOCH=18-APR-2016:00:00:00, EpochTimeScale=TDB ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 19 +/- 2 Ephemeris Center: EARTH Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 14524( 3) - 29-Jun-2016 16:05:38 - [ 3] Visit: 01 Visit Requirements: BEFORE 03-JUL-2016:06:00:00 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 P2016-G1 WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 3 420 S SEQ 1-2 NON-INT S (1260 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 P2016-G1 WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 2 420 S (840 POS TARG 0.2, 2.0 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 | ------------------------------------------------------------------------------------------------------------------------------------ P2016-G1 1 WFC3/UVI ACCUM UVIS2 F350LP none none 1 none 1 N/A S P2016-G1 1 WFC3/UVI ACCUM UVIS2 F350LP none none 2 none 1 N/A S P2016-G1 1 WFC3/UVI ACCUM UVIS2 F350LP none none 3 none 1 N/A S P2016-G1 2 WFC3/UVI ACCUM UVIS2 F350LP none none 1 none 1 N/A S P2016-G1 2 WFC3/UVI ACCUM UVIS2 F350LP none none 2 none 1 N/A S 14524( 3) - 29-Jun-2016 16:05:38 - [ 4] Visit: 02 Visit Requirements: AFTER 01 BY 12 D TO 22 D 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 P2016-G1 WFC3/UVI ACCUM UVIS2 F350LP CR-SPLIT=NO 4 580 S SEQ 1 NON-INT S (2320 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 | ------------------------------------------------------------------------------------------------------------------------------------ P2016-G1 1 WFC3/UVI ACCUM UVIS2 F350LP none none 1 none 1 N/A S P2016-G1 1 WFC3/UVI ACCUM UVIS2 F350LP none none 2 none 1 N/A S P2016-G1 1 WFC3/UVI ACCUM UVIS2 F350LP none none 3 none 1 N/A S P2016-G1 1 WFC3/UVI ACCUM UVIS2 F350LP none none 4 none 1 N/A S 14524( 3) - 29-Jun-2016 16:05:38 - [ 5] Summary Form for Proposal 14524 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 12 D TO 22 D, BEFORE 03-JUL-2016:06:00:00, POS TARG 0.2, 2.0, SEQ 1 NON-INT, SEQ 1-2 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F350LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names P2016-G1 ------------------------------------------------------------------------------------------------------------------------------------