16315( 6) - 22-Feb-2021 13:24:35 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16315 Version: 6 Check-in Time: 22-Feb-2021 13:24:35 STScI Edit Number: 3 Title Drivers of Activity for Interstellar object 2I/2019 Q4 (Borisov) ------------------------------------------------------------------------------------ Type Cycle GO 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Karen J. Meech University of Hawaii Y CoI: Dr. Marc W. Buie Southwest Research Institute Y CoI: Dr. Jacqueline Keane University of Hawaii Y CoI: Dr. Jan Kleyna University of Hawaii N CoI: Olivier Raoul Hainaut European Southern Observatory - Germany N CoI: Dr. Bin Yang European Southern Observatory - Chile N CoI: Dr. Davide Farnocchia Jet Propulsion Laboratory N CoI: Dr. Marco Micheli ESA NEO Coordination Centre N CoI: Dr. Coryn A. L. Bailer-Jones Max-Planck-Institut fur Astronomie, N Heidelberg CoI: Prof. Dina Prialnik Tel Aviv University N CoI: Dr. Hermann Boehnhardt Max Planck Institute for Solar System N Research CoI: Erica Bufanda University of Hawaii N CoI: Dr. David Tholen University of Hawaii N CoI: Dr. Richard Wainscoat University of Hawaii N ------------------------------------------------------------------------------------ Abstract We request 5 orbits to observe the interstellar object 2I/2019 Q4 (Borisov) during the post-perihelion portion of its orbit, once it comes out of the HST solar avoidance region in mid-January 2021. Photometry from HST and from the ground shows that the comet is still bright, consistent with continued CO-driven activity, and that it is likely still to be bright enough to observe when it emerges again from solar conjunction. The requested data will be combined with high quality ground-based data, and HST imaging data obtained from several programs to perform detailed thermal modeling of the comet's activity, search for structures in the coma, and to perform high precision astrometry on the outbound orbit to model the non-gravitational forces acting on the nucleus. This is a unique object, only the second of its class discovered. 2I is now past perihelion at a heliocentric distance of 2.7 au and is heading out of the solar system and will never return. There is intense scientific interest in this object because it is likely a remnant of the planet building process from an exoplanetary system that we have been given the opportunity to observe in close detail, thus it is important to finish the observations necessary to fully utilize the huge scientific investment already made on this object. ------------------------------------------------------------------------------------ Observations Description ------------------------ Each visit is nearly identical in design, five long exposures that fill the observing window with dithering. The full field of WFC3 is used to facilitate our high-precision astrometric goals. The only difference between the visits is 16315( 6) - 22-Feb-2021 13:24:35 - [ 2] a time constraint. The design is based on the goal of getting regularly spaced observations during Cycle 28 after the target comes out of solar exclusion. Each visit is given a 2 week window for scheduling and the visits are to be spaced 6 weeks apart. This plan assumes the target will continue to be detectable through the entire period of observation and will not be detectable after our last visit. However, the predicted brightness is quite uncertain because the level of outgassing is not known (and is one of our measurement objectives). There is a chance that if all activity stops that the target could be too faint to detect later in the Cycle. Prior to scheduling these observations we will be updating our models of the predicted brightness. If there is no chance of detecting the target we would release the allocated time. There is an intermediate case where the visits can be combined to reach a deeper limiting magnitude at the expense of fewer epochs. Any adjustments in the visit timing will be made early enough to not impact the usual flow of scheduling observations. ------------------------------------------------------------------------------------ 16315( 6) - 22-Feb-2021 13:24:35 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: I2-BOROSOV ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: COMET Interstellar Object ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 TYPE=COMET, Q=2.006624008587265, E=3.356191268153205, I=44.05262620283894 , O=308.1489154698829, W=209.1246056235187, T=08-DEC-2019:13:04:38, TTimeScale=TDB, EQUINOX=J2000, EPOCH=31-JUL-2020:00:00:00, EpochTimeScale=TDB, R0=2.808 , DT=0. , A1=7.312064170837E-8, A2=-3.252092599869E-8, A3=0. , ALN=0.1112620426, NM=2.15, NN=5.093, NK=4.6142, AMRAT=0. ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 26 +/- 3 Ephemeris Center: EARTH ------------------------------------------------------------------------------------------------------------------------------------ 16315( 6) - 22-Feb-2021 13:24:35 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type LINE Pattern_Purpose OTHER Number_Of_Points 5 Point_Spacing 0.03 Line_Spacing Coordinate_Frame CELESTIAL Pattern_Orient 0 Angle_Between_Sides Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ 16315( 6) - 22-Feb-2021 13:24:35 - [ 5] Visit: 01 (AST01) Visit Requirements: BETWEEN 29-JAN-2021:19:51:00 AND 29-JAN-2021:20:11:00; BETWEEN 31-JAN-2021:13:12 AND 31-JAN-2021:13:22; BETWEEN 01-FEB-2021:13:00 AND 01-FEB-2021:16:21; BETWEEN 02-FEB-2021:11:14 AND 02-FEB-2021:13:00; BETWEEN 02-FEB-2021:15:59 AND 02-FEB-2021:16:09; BETWEEN 02-FEB-2021:19:10 AND 02-FEB-2021:19:20 On Hold Comments: Additional Comments: The five long, dithered exposures are intended to fill a single visibility window to get the relative timing we need. This is a stand-alone visit with a window provided to give a time constraint that is loose but holds it in roughly the right timeframe for the overall temporal sequence needed for the observing. Successful observations require a minimum number of suitable Gaia DR2 sources in the full field of UVIS. As the observations are scheduled, the proposal team needs to check potential windows for suitable guide stars and avoidance of field star contamination of the target and provide guidance on which windows will work best. If the fields are sparse enough, we may need to provide adjusted POSTARG values to ensure there are enough stars. 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 I2-BOROSOV WFC3/UVI ACCUM UVIS F350LP 1 380 S SEQ 1 NON-INT; PATTERN 1 S (1900 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 1 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 2 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 3 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 4 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 5 none none none 1 N/A S 16315( 6) - 22-Feb-2021 13:24:35 - [ 6] Visit: 02 (AST02) Visit Requirements: BETWEEN 17-MAR-2021:00:00:00 AND 31-MAR-2021:00:00:00; SEQ 02, 03, 04, 05 WITHIN 12 H On Hold Comments: Additional Comments: The five long, dithered exposures are intended to fill a single visibility window to get the relative timing we need. This is a stand-alone visit with a window provided to give a time constraint that is loose but holds it in roughly the right timeframe for the overall temporal sequence needed for the observing. Successful observations require a minimum number of suitable Gaia DR2 sources in the full field of UVIS. As the observations are scheduled, the proposal team needs to check potential windows for suitable guide stars and avoidance of field star contamination of the target and provide guidance on which windows will work best. If the fields are sparse enough, we may need to provide adjusted POSTARG values to ensure there are enough stars. The plan is revised based on the non-detection of the object in visit 01. The revision calls for using visit 2-5 in aggregate to generate a deep stack from which to detect the target. These visits should be scheduled as close together as possible. We still need to review the scheduling windows for stellar contamination. 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 I2-BOROSOV WFC3/UVI ACCUM UVIS F350LP 1 380 S SEQ 1 NON-INT; PATTERN 1 S (1900 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 1 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 2 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 3 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 4 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 5 none none none 1 N/A S 16315( 6) - 22-Feb-2021 13:24:35 - [ 7] Visit: 03 (AST03) Visit Requirements: On Hold Comments: Additional Comments: The five long, dithered exposures are intended to fill a single visibility window to get the relative timing we need. This is a stand-alone visit with a window provided to give a time constraint that is loose but holds it in roughly the right timeframe for the overall temporal sequence needed for the observing. Successful observations require a minimum number of suitable Gaia DR2 sources in the full field of UVIS. As the observations are scheduled, the proposal team needs to check potential windows for suitable guide stars and avoidance of field star contamination of the target and provide guidance on which windows will work best. If the fields are sparse enough, we may need to provide adjusted POSTARG values to ensure there are enough stars. 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 I2-BOROSOV WFC3/UVI ACCUM UVIS F350LP 1 380 S SEQ 1 NON-INT; PATTERN 1 S (1900 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 1 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 2 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 3 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 4 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 5 none none none 1 N/A S 16315( 6) - 22-Feb-2021 13:24:35 - [ 8] Visit: 04 (AST04) Visit Requirements: On Hold Comments: Additional Comments: The five long, dithered exposures are intended to fill a single visibility window to get the relative timing we need. This is a stand-alone visit with a window provided to give a time constraint that is loose but holds it in roughly the right timeframe for the overall temporal sequence needed for the observing. Successful observations require a minimum number of suitable Gaia DR2 sources in the full field of UVIS. As the observations are scheduled, the proposal team needs to check potential windows for suitable guide stars and avoidance of field star contamination of the target and provide guidance on which windows will work best. If the fields are sparse enough, we may need to provide adjusted POSTARG values to ensure there are enough stars. 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 I2-BOROSOV WFC3/UVI ACCUM UVIS F350LP 1 380 S SEQ 1 NON-INT; PATTERN 1 S (1900 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 1 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 2 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 3 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 4 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 5 none none none 1 N/A S 16315( 6) - 22-Feb-2021 13:24:35 - [ 9] Visit: 05 (AST05) Visit Requirements: On Hold Comments: Additional Comments: The five long, dithered exposures are intended to fill a single visibility window to get the relative timing we need. This is a stand-alone visit with a window provided to give a time constraint that is loose but holds it in roughly the right timeframe for the overall temporal sequence needed for the observing. Successful observations require a minimum number of suitable Gaia DR2 sources in the full field of UVIS. As the observations are scheduled, the proposal team needs to check potential windows for suitable guide stars and avoidance of field star contamination of the target and provide guidance on which windows will work best. If the fields are sparse enough, we may need to provide adjusted POSTARG values to ensure there are enough stars. 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 I2-BOROSOV WFC3/UVI ACCUM UVIS F350LP 1 380 S SEQ 1 NON-INT; PATTERN 1 S (1900 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 1 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 2 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 3 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 4 none none none 1 N/A S I2-BOROSOV 1 WFC3/UVI ACCUM UVIS F350LP 5 none none none 1 N/A S 16315( 6) - 22-Feb-2021 13:24:35 - [ 10] Summary Form for Proposal 16315 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-FEB-2021:13:00 AND 01-FEB-2021:16:21, BETWEEN 02-FEB-2021:11:14 AND 02-FEB-2021:13:00, BETWEEN 02-FEB-2021:15:59 AND 02-FEB-2021:16:09, BETWEEN 02-FEB-2021:19:10 AND 02-FEB-2021:19:20, BETWEEN 17-MAR-2021:00:00:00 AND 31-MAR-2021:00:00:00, BETWEEN 29-JAN-2021:19:51:00 AND 29-JAN-2021:20:11:00, BETWEEN 31-JAN-2021:13:12 AND 31-JAN-2021:13:22, PATTERN 1 1, SEQ 02, 03, 04, 05 WITHIN 12 H, SEQ 1 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F350LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names I2-BOROSOV ------------------------------------------------------------------------------------------------------------------------------------