16112( 9) - 09-Sep-2020 14:18:06 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16112 Version: 9 Check-in Time: 09-Sep-2020 14:18:06 STScI Edit Number: 7 Title HIgh-precision astrometry of (15094) Polymele in support of the Lucy Mission ------------------------------------------------------------------------------------ Type Cycle GO/DD 27 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Marc W. Buie Southwest Research Institute Y CoI: Dr. Keith S. Noll NASA Goddard Space Flight Center N CoI: Dr. Harold F. Levison Southwest Research Institute N CoI: Dr. Catherine Olkin Southwest Research Institute N ------------------------------------------------------------------------------------ Abstract We propose a targeted set of observations of (15094) Polymele which is the smallest prime target for the Lucy mission. The goal of these observations is to get high-precision astrometry at three epochs. This astrometry will be used to reduce the uncertainties of Polymele's orbit estimate needed to enable a high-chord-density occultation observation later in 2020. ------------------------------------------------------------------------------------ Observations Description ------------------------ All visits are independent and identical except for when they need to execute. We will take 5 full-frame WFC3/UVIS images of the field containing Polymele. The exposure time is set to fully utilize the visibility window and small adjustments are acceptible to adapt to slight changes in the visibility window. The placement of Polymele is initially set for the default location (POSTARG=0). All observations will track Polymele meaning the stars will be trailed by target motion and HST motion-induced parallax. As work begins to schedule each visit, we need an opportunity to check the candidate windows for suitability. We have a system in place that allows checking for sufficient Gaia DR2 reference stars in the field and to avoid overlap with the target at the star trails given a table of candidate window from STScI. This is the same process that we have been using for all of our Arrokoth, Oumuamua, and Borisov observations with HST. Field star interference is grounds for rejecting a window. The use of POSTARG and small changes to roll angle are used in cases where the field star density is low and an adjustment is needed to increase the number of field stars. We will not use these adjustments unless absolutely necessary. They are not for optimizing the visit but rather to improve one option to get even a single candidate that will work. So far, that has only been necessary for the Oumuamua observations. For reference, getting 6 or so field stars has generally been good enough but having fewer means we will look for better options. The scheduling windows are meaningful but there is additional flexibility available if the initial windows prove to be too restrictive. Notionally, we want to attempt observations in June, July, and September. The overall requirement is to spread out the three visits between the end of the solar 16112( 9) - 09-Sep-2020 14:18:06 - [ 2] exclusion window and the occultation in September. The initial placement of the first two visits gives us a backup window in August in case one of these fails. The September window is set to be just before the occultation with sufficient width to be schedulable and provide sufficient time after observation to process the data, update the orbit fit, and provide an occultaiton prediction update. The end of the window is the more stringent constraint. ------------------------------------------------------------------------------------ 16112( 9) - 09-Sep-2020 14:18:06 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: POLYMELE ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: ASTEROID Lucy mission target ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 TYPE=ASTEROID, A=5.168430829356419, E=0.09482321984419208, I=12.98961897481968 , O=50.31762273700706, W=4.401542022614581, M=295.7073098559924, EQUINOX=J2000, EPOCH=05-AUG-2019:00:00:00, EpochTimeScale=TDB ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 19 +/- 0.2 Updates to the orbit during the execution of this program are unlikely. We have already worked with JPL to produce this orbit and any future updates will only be important Ephemeris Center: EARTH for occultaiton planning and not at all important for HST. ------------------------------------------------------------------------------------------------------------------------------------ 16112( 9) - 09-Sep-2020 14:18:06 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 16112( 9) - 09-Sep-2020 14:18:06 - [ 5] Visit: 01 (AST1) Visit Requirements: BETWEEN 01-JUN-2020:00:00:00 AND 15-JUN-2020:00:00:00 On Hold Comments: Additional Comments: All visits have the same structure with 5 long, dithered exposures that fill the orbit. The only variable is how the visits are scheduled. 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 POLYMELE WFC3/UVI ACCUM UVIS F350LP 1 380 S POS TARG 0, 0; SEQ 1 S (1900 S) NON-INT; PATTERN 1 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 | ------------------------------------------------------------------------------------------------------------------------------------ POLYMELE 1 WFC3/UVI ACCUM UVIS F350LP 1 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS F350LP 2 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS F350LP 3 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS F350LP 4 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS F350LP 5 none none none 1 N/A S 16112( 9) - 09-Sep-2020 14:18:06 - [ 6] Visit: 02 (AST2) Visit Requirements: BETWEEN 06-JUL-2020:18:30:00 AND 06-JUL-2020:19:30:00 On Hold Comments: Additional Comments: All visits have the same structure with 5 long, dithered exposures that fill the orbit. The only variable is how the visits are scheduled. 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 POLYMELE WFC3/UVI ACCUM UVIS F350LP 1 380 S POS TARG 0, 12; SEQ 1 S (1900 S) NON-INT; PATTERN 1 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 | ------------------------------------------------------------------------------------------------------------------------------------ POLYMELE 1 WFC3/UVI ACCUM UVIS F350LP 1 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS F350LP 2 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS F350LP 3 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS F350LP 4 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS F350LP 5 none none none 1 N/A S 16112( 9) - 09-Sep-2020 14:18:06 - [ 7] Visit: 03 (AST3) Visit Requirements: On Hold Comments: Additional Comments: All visits have the same structure with 5 long, dithered exposures that fill the orbit. The only variable is how the visits are scheduled. 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 POLYMELE WFC3/UVI ACCUM UVIS2 F350LP 1 380 S POS TARG 24.0, 26.0; SEQ S (1900 S) 1 NON-INT; PATTERN 1 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 | ------------------------------------------------------------------------------------------------------------------------------------ POLYMELE 1 WFC3/UVI ACCUM UVIS2 F350LP 1 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS2 F350LP 2 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS2 F350LP 3 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS2 F350LP 4 none none none 1 N/A S POLYMELE 1 WFC3/UVI ACCUM UVIS2 F350LP 5 none none none 1 N/A S 16112( 9) - 09-Sep-2020 14:18:06 - [ 8] Summary Form for Proposal 16112 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS, UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-JUN-2020:00:00:00 AND 15-JUN-2020:00:00:00, BETWEEN 06-JUL-2020:18:30:00 AND 06-JUL-2020:19:30:00, PATTERN 1 1, POS TARG 0, 0, POS TARG 0, 12, POS TARG 24.0, 26.0, SEQ 1 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F350LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names POLYMELE ------------------------------------------------------------------------------------------------------------------------------------