16501( 8) - 02-Sep-2021 16:56:10 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16501 Version: 8 Check-in Time: 02-Sep-2021 16:56:10 STScI Edit Number: 2 Title Is main-belt comet 288P a triple system? ------------------------------------------------------------------------------------ Type Cycle GO 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Yoonyoung Kim Technische Universitaet Braunschweig Y CoI: Dr. Jessica Agarwal Technische Universitaet Braunschweig Y CoI: Dr. David Jewitt University of California - Los Angeles N CoI: Max Mutchler Space Telescope Science Institute Y CoI: Dr. Harold A. Weaver The Johns Hopkins University Applied N Physics Laboratory CoI: Dr. Stephen M. Larson University of Arizona N ------------------------------------------------------------------------------------ Abstract We request 6 mid-cycle orbits using WFC3 in 2021 June to probe the newly suspected triple nature of main-belt comet 288P. This object is unique. It has wide separation, nearly equal-sized components, and also displays repetitive comet-like activity. 288P is one of only a few known asteroid binaries whose components can be spatially resolved by WFC3. Archival WFC3 observations obtained two months after the Cycle 28 deadline reveal that 288P is likely triple. That is, the light curve of one of the two main components is best represented as the sum of the lightcurves of two (spatially unresolved) components with different periods. Additional data are needed to confirm the third component. Successful identification of the third component would make 288P the first-ever detected triple asteroid system to exhibit comet-like activity, and provide crucial constraints on asteroid break-up models and on the role of activity-causing ice sublimation. We emphasize that these measurements maximally exploit the capabilities of HST for high resolution imaging. HST is the only telescope able to spatially separate the two main nuclei (maximum separation about 0.1 arcsec) and hence to measure their rotational lightcurves separately. The proposed observations are time-critical to be carried out in 2021 June, which is the last opportunity to spatially separate the two main components before the return of dust activity in fall 2021. ------------------------------------------------------------------------------------ Observations Description ------------------------ The goal of this program is to measure the time-variability of the brightness of the two components of binary asteroid 288P. We expect that the components will be separated by <0.1arcsec in 2021 September and have a combined brightness of about V=22mag. All 6 visits should be scheduled as close in time as possible, ideally as 3 pairs of orbits separated each by only one orbit for gyro reset. But distributing the orbits across a time interval of ~24h will also be acceptable (which can be relaxed as needed for scheduling). Hence the timing requirements are as follows: 16501( 8) - 02-Sep-2021 16:56:10 - [ 2] Visit 1: BETWEEN Sep 27 and Oct 01, GROUP Visits 01, 02, 03 WITHIN 24H Each visit consists of 8 exposures of ~240s, using a 2-point linear dither pattern to mitigate bad pixels and the C512C sub-frame to minimise read-out time. If the actual orbital visibility is shorter than expected in APT, then the exposure time can be shortened such that all 8 exposures fit into one orbit. Should the program have to be carried out in 1gyro mode we can shorten the exposure time to adapt to the increased time for guide star acquisition. The target will be at solar elongations >110deg, hence the enlarged solar exclusion zone will not pose a problem. ------------------------------------------------------------------------------------ 16501( 8) - 02-Sep-2021 16:56:10 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 TARGET NAME: 288P-UPDATE3 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID binary asteroid ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 TYPE=ASTEROID, A=3.049316706845886, E=0.2011145348983784, I=3.240027217147757 , O=83.18987601023933, W=281.0531996557008, M=359.7694035685469, EQUINOX=J2000, EPOCH=07-NOV-2016:00:00:00, EpochTimeScale=TDB ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 22 +/- 0.5 Ephemeris Center: EARTH Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 16501( 8) - 02-Sep-2021 16:56:10 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.145 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 16501( 8) - 02-Sep-2021 16:56:10 - [ 5] Visit: 01 Visit Requirements: BETWEEN 27-SEP-2021:00:00:00 AND 27-SEP-2021:21:45:00; BETWEEN 28-SEP-2021:00:08:00 AND 28-SEP-2021:06:30:00; BETWEEN 28-SEP-2021:08:53:00 AND 29-SEP-2021:15:00:00; BETWEEN 29-SEP-2021:19:00:00 AND 30-SEP-2021:08:00:00; BETWEEN 30-SEP-2021:13:00:00 AND 01-OCT-2021:13:00:00; GROUP 01, 02, 03 WITHIN 24H 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 288P-UPDATE WFC3/UVI ACCUM UVIS2-C51 F606W 4 237 S SEQ 1 NON-INT; PATTERN 1 3 S 2C-SUB (1896 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 288P-UPDATE WFC3/UVI ACCUM UVIS2-C51 F606W 4 237 S SEQ 2 NON-INT; PATTERN 1 3 S 2C-SUB (1896 S) 2 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 1 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 2 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 3 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 4 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 1 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 2 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 3 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 4 none 1 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 1 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 2 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 3 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 4 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 1 none 2 N/A S 12C-SUB 16501( 8) - 02-Sep-2021 16:56:10 - [ 6] 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 | ------------------------------------------------------------------------------------------------------------------------------------ 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 2 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 3 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 4 none 2 N/A S 12C-SUB 16501( 8) - 02-Sep-2021 16:56:10 - [ 7] Visit: 02 Visit Requirements: BETWEEN 27-SEP-2021:00:00:00 AND 27-SEP-2021:21:45:00; BETWEEN 28-SEP-2021:00:08:00 AND 28-SEP-2021:06:30:00; BETWEEN 28-SEP-2021:08:53:00 AND 29-SEP-2021:15:00:00; BETWEEN 29-SEP-2021:19:00:00 AND 30-SEP-2021:08:00:00; BETWEEN 30-SEP-2021:13:00:00 AND 01-OCT-2021:13:00:00 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 288P-UPDATE WFC3/UVI ACCUM UVIS2-C51 F606W 4 237 S SEQ 1 NON-INT; PATTERN 1 3 S 2C-SUB (1896 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 288P-UPDATE WFC3/UVI ACCUM UVIS2-C51 F606W 4 237 S SEQ 2 NON-INT; PATTERN 1 3 S 2C-SUB (1896 S) 2 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 1 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 2 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 3 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 4 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 1 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 2 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 3 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 4 none 1 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 1 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 2 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 3 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 4 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 1 none 2 N/A S 12C-SUB 16501( 8) - 02-Sep-2021 16:56:10 - [ 8] 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 | ------------------------------------------------------------------------------------------------------------------------------------ 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 2 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 3 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 4 none 2 N/A S 12C-SUB 16501( 8) - 02-Sep-2021 16:56:10 - [ 9] Visit: 03 Visit Requirements: BETWEEN 27-SEP-2021:00:00:00 AND 27-SEP-2021:21:45:00; BETWEEN 28-SEP-2021:00:08:00 AND 28-SEP-2021:06:30:00; BETWEEN 28-SEP-2021:08:53:00 AND 29-SEP-2021:15:00:00; BETWEEN 29-SEP-2021:19:00:00 AND 30-SEP-2021:08:00:00; BETWEEN 30-SEP-2021:13:00:00 AND 01-OCT-2021:13:00:00 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 288P-UPDATE WFC3/UVI ACCUM UVIS2-C51 F606W 4 237 S SEQ 1 NON-INT; PATTERN 1 3 S 2C-SUB (1896 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 288P-UPDATE WFC3/UVI ACCUM UVIS2-C51 F606W 4 237 S SEQ 2 NON-INT; PATTERN 1 3 S 2C-SUB (1896 S) 2 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 1 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 2 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 3 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 4 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 1 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 2 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 3 none 1 N/A S 12C-SUB 288P-UPDATE3 1 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 4 none 1 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 1 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 2 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 3 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 1 none 4 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 1 none 2 N/A S 12C-SUB 16501( 8) - 02-Sep-2021 16:56:10 - [ 10] 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 | ------------------------------------------------------------------------------------------------------------------------------------ 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 2 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 3 none 2 N/A S 12C-SUB 288P-UPDATE3 2 WFC3/UVI ACCUM UVIS2-C5 F606W 2 none 4 none 2 N/A S 12C-SUB 16501( 8) - 02-Sep-2021 16:56:10 - [ 11] Summary Form for Proposal 16501 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2-C512C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 27-SEP-2021:00:00:00 AND 27-SEP-2021:21:45:00, BETWEEN 28-SEP-2021:00:08:00 AND 28-SEP-2021:06:30:00, BETWEEN 28-SEP-2021:08:53:00 AND 29-SEP-2021:15:00:00, BETWEEN 29-SEP-2021:19:00:00 AND 30-SEP-2021:08:00:00, BETWEEN 30-SEP-2021:13:00:00 AND 01-OCT-2021:13:00:00, GROUP 01, 02, 03 WITHIN 24H, PATTERN 1 1, PATTERN 1 2, SEQ 1 NON-INT, SEQ 2 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names 288P-UPDATE3 ------------------------------------------------------------------------------------------------------------------------------------