17473( 5) - 10-Jun-2024 14:31:48 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17473 Version: 5 Check-in Time: 10-Jun-2024 14:31:48 STScI Edit Number: 3 Title Moving beyond the Milky Way: Enabling Cross-Observatory Proper Motion Determinations with HST and JWST ------------------------------------------------------------------------------------ Type Cycle GO 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Jack Thomas Warfield The University of Virginia Y CoI: Dr. Nitya Kallivayalil The University of Virginia N CoI: Ms. Hannah Richstein The University of Virginia N CoI: Dr. Christopher Garling The University of Virginia N CoI: Dr. Alessandro Savino University of California - Berkeley N CoI: Dr. Martha L. Boyer Space Telescope Science Institute N CoI: Dr. Jay Anderson Space Telescope Science Institute N CoI: Prof. Andrew A. Cole University of Tasmania N CoI: Dr. Karin Marie Sandstrom University of California - San Diego N CoI: Dr. Kristen B W McQuinn Space Telescope Science Institute N CoI: Dr. Sangmo Tony Sohn Space Telescope Science Institute N CoI: Dr. Andrew Eugene Dolphin Raytheon Company N CoI: Dr. Roger Cohen Rutgers the State University of New Jersey N CoI: Dr. Matteo Correnti INAF, Osservatorio Astronomico di Roma N CoI: Dr. Evan D. Skillman University of Minnesota - Twin Cities N CoI: Dr. Daniel R. Weisz University of California - Berkeley N CoI: Prof. Marla C. Geha Yale University N CoI: Max J. B. Newman Rutgers the State University of New Jersey N ------------------------------------------------------------------------------------ Abstract HST has made unique contributions to our understanding of the dynamical evolution of the Milky Way and its constituent satellites, globular clusters, halo stars and tidal streams. Proper motions enabled by multi-epoch HST observations have been used to probe the nature of dark matter, the epoch of reionization, and correlated satellite infall. While Gaia now, too, provides unparalleled astrometric precision for the Milky Way, at outer halo distances this is only for intrinsically bright stars. Moving beyond the Milky Way halo will only be possible by utilizing long baselines with HST or by extending these baselines using another facility, such as JWST or Roman, in tandem with a first epoch from HST. Thus, it is imperative that we calibrate cross-observatory techniques to measure absolute proper motions. Here, we request 8 orbits with ACS/WFC and 3.27 hours with JWST's NIRCam for Draco II, an ultra-faint dwarf galaxy, and WLM, a star-forming galaxy. Both objects already have an epoch of ACS/WFC data, as well as publicly available NIRCam data from the Resolved Stellar Populations Early Release Science program. We will use the newly requested data to measure an HST-HST proper motion for each dwarf. This proper motion will be used as a "ground truth" to investigate and calibrate (i) detector-based systematics and (ii) reference frame-based systematics, in combining HST and JWST data. We stress the urgency of getting these observations now while HST is operating well. Such cross-observatory calibrations will be extremely difficult if the astrometric capabilities of HST degrade. ------------------------------------------------------------------------------------ 17473( 5) - 10-Jun-2024 14:31:48 - [ 2] Observations Description ------------------------ We will observe Draco II - an ultra-faint dwarf galaxy - and WLM - a star-forming, isolated dwarf galaxy - with ACS/WFC, using 4 orbits for each target. Both objects already have an epoch of ACS/WFC data, as well as deep NIRCam data in two SW filters. This new data can be used to measure an HST-HST proper motion for each dwarf galaxy, which can serve as a "ground truth" to investigate and calibrate (i) detector-based systematics and (ii) refrence frame-based systematics in combining HST and JWST data. In this program, each target field will be observed using the same telescope pointings and orientations as the first-epoch images to maximize the overlaps of the observed fields between first- and second-epoch data. This will also minimize position-dependent uncertainties originating from imperfect CTE and geometric distortion corrections. These observations will be made in the F814W filter, which has proven to give the best astrometric handle on background galaxies, and which is also one of the filters used for the first-epoch observations of both targets. Two exposures per orbit will be taken in order to complete and eight-point dither, allowing for deep single-exposure images that together allow for a well-sampled PSF. ------------------------------------------------------------------------------------ 17473( 5) - 10-Jun-2024 14:31:48 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-DRACO-I GALAXY, DWARF RA=15H52M47.3483S, J2000 M_V=-2.9 I SPHEROIDAL DEC=+64D33'56.00" Reference Frame: Other: SIMBAD Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 8.382181051432045E-5 9.400000000000001E-4 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 WLM GALAXY, DWARF RA=00H01M57.3000S, J2000 V = 19 +/- 1 ELLIPTICAL DEC=-15D31'22.70" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 17473( 5) - 10-Jun-2024 14:31:48 - [ 4] Visit: 01 (Draco II) Visit Requirements: SCHED 30%; ORIENT 243.4269015D TO 243.4269015 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 NAME-DRACO- ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.0, 0.0; GS II see below ACQ SCENARIO BASE1B3 (1322 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-DRACO- ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.1740, 0.2350 II see below (1322 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NAME-DRACO- ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.3232, 0.1235 II see below (1359 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 NAME-DRACO- ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.1005, 0.3305 II see below (1359 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 | ------------------------------------------------------------------------------------------------------------------------------------ NAME-DRACO-II 1 ACS/WFC ACCUM WFC F814W none none none none 1 1322.0 S NAME-DRACO-II 2 ACS/WFC ACCUM WFC F814W none none none none 1 1322.0 S NAME-DRACO-II 3 ACS/WFC ACCUM WFC F814W none none none none 2 1359.0 S NAME-DRACO-II 4 ACS/WFC ACCUM WFC F814W none none none none 2 1359.0 S 17473( 5) - 10-Jun-2024 14:31:48 - [ 5] Visit: 02 (WLM) Visit Requirements: SCHED 30%; ORIENT 257.943153D TO 257.943153 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 WLM ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.0, 0.0; GS see below ACQ SCENARIO BASE1O3 (1189 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 WLM ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.1740, 0.2350 see below (1189 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 WLM ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.3232, 0.1235 see below (1225 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 WLM ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.1005, 0.3305 see below (1225 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 | ------------------------------------------------------------------------------------------------------------------------------------ WLM 1 ACS/WFC ACCUM WFC F814W none none none none 1 1189.0 S WLM 2 ACS/WFC ACCUM WFC F814W none none none none 1 1189.0 S WLM 3 ACS/WFC ACCUM WFC F814W none none none none 2 1225.0 S WLM 4 ACS/WFC ACCUM WFC F814W none none none none 2 1225.0 S 17473( 5) - 10-Jun-2024 14:31:48 - [ 6] Visit: 03 (Draco II) Visit Requirements: SCHED 30%; ORIENT 243.4269015D TO 243.4269015 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 NAME-DRACO- ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.5075, 0.0505; II see below GS ACQ SCENARIO BASE1B3 (1322 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-DRACO- ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.6815, 0.2855 II see below (1322 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NAME-DRACO- ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.8300, 0.1735 II see below (1359 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 NAME-DRACO- ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.6080, 0.3810 II see below (1359 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 | ------------------------------------------------------------------------------------------------------------------------------------ NAME-DRACO-II 1 ACS/WFC ACCUM WFC F814W none none none none 1 1322.0 S NAME-DRACO-II 2 ACS/WFC ACCUM WFC F814W none none none none 1 1322.0 S NAME-DRACO-II 3 ACS/WFC ACCUM WFC F814W none none none none 2 1359.0 S NAME-DRACO-II 4 ACS/WFC ACCUM WFC F814W none none none none 2 1359.0 S 17473( 5) - 10-Jun-2024 14:31:48 - [ 7] Visit: 04 (WLM) Visit Requirements: SCHED 30%; ORIENT 257.943153D TO 257.943153 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 WLM ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.5075, 0.0505; see below GS ACQ SCENARIO BASE1O3 (1189 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 WLM ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.6815, 0.2855 see below (1189 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 WLM ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.8300, 0.1735 see below (1225 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 WLM ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 1151 S POS TARG 0.6080, 0.3810 see below (1225 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 | ------------------------------------------------------------------------------------------------------------------------------------ WLM 1 ACS/WFC ACCUM WFC F814W none none none none 1 1189.0 S WLM 2 ACS/WFC ACCUM WFC F814W none none none none 1 1189.0 S WLM 3 ACS/WFC ACCUM WFC F814W none none none none 2 1225.0 S WLM 4 ACS/WFC ACCUM WFC F814W none none none none 2 1225.0 S 17473( 5) - 10-Jun-2024 14:31:48 - [ 8] Summary Form for Proposal 17473 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1B3, GS ACQ SCENARIO BASE1O3, ORIENT 243.4269015D TO 243.4269015 D, ORIENT 257.943153D TO 257.943153 D, POS TARG 0.0, 0.0, POS TARG 0.1005, 0.3305, POS TARG 0.1740, 0.2350, POS TARG 0.3232, 0.1235, POS TARG 0.5075, 0.0505, POS TARG 0.6080, 0.3810, POS TARG 0.6815, 0.2855, POS TARG 0.8300, 0.1735, SCHED 30% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NAME-DRACO-II, WLM ------------------------------------------------------------------------------------------------------------------------------------