17277( 2) - 09-Dec-2022 16:01:28 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17277 Version: 2 Check-in Time: 09-Dec-2022 16:01:28 STScI Edit Number: 0 Title Spatially Resolving the First z>1 Fast Radio Burst Host Galaxy ------------------------------------------------------------------------------------ Type Cycle GO 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Mrs. Alexa Gordon Northwestern University Y CoI: Dr. Wen-fai Fong Northwestern University N CoI: Dr. Charles Kilpatrick Northwestern University N CoI: Dr. Jason X. Prochaska University of California - Santa Cruz N CoI: Mr. Sunil Simha University of California - Santa Cruz N CoI: Dr. Nicolas Tejos Pontificia Universidad Catolica de N Valparaiso CoI: Dr. Marc Rafelski Space Telescope Science Institute Y CoI: Dr. Kameswara Bharadwaj Mantha University of Minnesota - Twin Cities N CoI: Dr. Ryan Shannon Swinburne University of Technology N CoI: Dr. Adam Travis Deller Swinburne University of Technology N CoI: Dr. Stuart Ryder Macquarie University N CoI: Lachlan Marnoch Macquarie University N ------------------------------------------------------------------------------------ Abstract Fast radio bursts (FRBs) are bright millisecond pulses that are prolific in the universe but have uncertain progenitors. The recent localization of FRB 20220610A to a z~1 host galaxy marked a new era in FRB science. As the furthest securely-localized FRB to date by a factor of two and most energetic by a factor of four, this burst is already revolutionizing our understanding of these events. In particular, this FRB directly probed ionized gas and magnetic fields in the intergalactic medium to times approaching the peak of cosmic star formation. Given the uncertainty of FRB progenitors, host galaxy environments offer vital clues. However, current ground-based imaging of FRB 20220610A reveals a complex host galaxy structure, suggestive of multiple galaxies and possibly indicative of an ongoing galaxy merger. As these data cannot resolve the components individually, we propose 4 orbits of HST imaging to discern the true morphology of this system, potentially uncover signs of a galaxy-scale merger, and delineate how this FRB traces its host galaxy's star formation and stellar mass distributions. These observations will give clear context for the proper interpretation of the ground-based observations and provide a key puzzle piece to the first FRB at z~1. ------------------------------------------------------------------------------------ Observations Description ------------------------ This program images a newly discovered FRB host galaxy at z~1 to measure the morphological structure of a complex host galaxy, suggestive of multiple galaxies and possibly indicative of an ongoing galaxy merger. As current ground-based data cannot resolve the components individually, we will use HST imaging to discern the true morphology of this system, potentially uncover signs of a galaxy-scale merger, and delineate how this FRB traces its host galaxy's star formation and stellar mass distributions. 17277( 2) - 09-Dec-2022 16:01:28 - [ 2] The rest-frame NUV (observed optical) will be sampled by the WFC3/UVIS F606W filter tracing recent star formation via young stars and yielding the highest possible resolution to distinguish the nature of the three components. The rest-frame optical (observed NIR) will be sampled by the WFC3/IR F160W filter. This is the reddest wide filter available on HST to measure the distribution of the stellar mass as traced by the old stellar populations. In order to obtain images clean of cosmic rays and image artifacts and sampling the PSF phase, we use custom dither patterns with 6 and 8 positions. For the optical measurements we will obtain six exposures, which also ensures no saturation for our somewhat bright target. Given the high background in the wide F606W bandpass, no post-flash is necessary. To minimize our pixel-based CTE correction, we place the target on chip 2 close to the readout. For the NIR observations, we wish to stay in the linear regime and minimize persistence with our bright target, and therefore will use SPAR50 with NSAMP of 13. Since this sets the exposure time per dither position, we end up with 4 dither positions per orbit for a total of 8 dither positions. As requested in the Phase I, to avoid a larger 4 orbit visit, we break up the filters into two orbits each and tie the orientations of the two filters to each other (within 5 degrees) to ensure sufficient targets in common to align the images to each other preceisely. We use a pos-targ offset of -55" and -45" in x and y, respectively, to align the IR detector on the WFC3/UVIS CTE aperture. For the WFC3/UVIS exposures, we use a dither pattern that is 5 times the custom 6 point dither pattern from WFC3/UVIS ISR 2020-07 (pg 14) to remove residual background patterns. For the WFC3/IR exposures, we use the 8-point wide dither pattern from WFC3/IR ISR 2016-14 (pg 17) to get a good dither for the pixel phase and artifiact mitigation. We multiply those values by 3 to better deal with IR blobs and self persistence. The large number of dithers for the IR is due to the desire to use SPAR50 as described above. We note that there is a 10th magnitude star in the upper north-west of our potential field of view. If scheduled at a PA of around 125 degrees, the star would fall on Chip 1, but the optical ghosts would fall in a favorable direction away from our target. However, if we are at a PA of around 110 degrees, there may be dragons breath on the detector. We believe that it would not impact the science target based on the orientation and the location of our science target, but if this is not the case, please reach out to the observers. We do not forsee any issues if we have to go to 1 gyro mode as we can observe at any absolute orientation, we just need the orientation of our two filters to be matched. If they can't be matched, we can also adjust the post-targ to allow different orientations between the visits as needed. ------------------------------------------------------------------------------------ 17277( 2) - 09-Dec-2022 16:01:28 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 FRB20220610A GALAXY, AMORPHOUS RA=23H24M17.6359S, J2000 V = 23.9 +/- 0.1 IRREGULAR, INTERACTING DEC=-33D30'49.18" GALAXY, MULTIPLE NUCLEI Reference Frame: ICRS Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 17277( 2) - 09-Dec-2022 16:01:28 - [ 4] Visit: 01 Visit Requirements: 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 FRB20220610 WFC3/UVI ACCUM UVIS2-C1K F606W 1 830 S A S 1C-CTE see below (844 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 FRB20220610 WFC3/UVI ACCUM UVIS2-C1K F606W 1 830 S POS TARG 0.4635, 1.6880 A S 1C-CTE see below (844 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 FRB20220610 WFC3/UVI ACCUM UVIS2-C1K F606W 1 830 S POS TARG 0.9255, 0.9890 A S 1C-CTE see below (844 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 FRB20220610 WFC3/UVI ACCUM UVIS2-C1K F606W 1 830 S POS TARG 1.1910, 2.5650 A S 1C-CTE see below (841 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 FRB20220610 WFC3/UVI ACCUM UVIS2-C1K F606W 1 830 S POS TARG 1.6525, 1.8660 A S 1C-CTE see below (841 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 FRB20220610 WFC3/UVI ACCUM UVIS2-C1K F606W 1 830 S POS TARG 2.5120, 2.5855 A S 1C-CTE see below (841 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 | ------------------------------------------------------------------------------------------------------------------------------------ FRB20220610A 1 WFC3/UVI ACCUM UVIS2-C1 F606W none none none none 1 844.0 S S K1C-CTE FRB20220610A 2 WFC3/UVI ACCUM UVIS2-C1 F606W none none none none 1 844.0 S S K1C-CTE FRB20220610A 3 WFC3/UVI ACCUM UVIS2-C1 F606W none none none none 1 844.0 S S K1C-CTE FRB20220610A 4 WFC3/UVI ACCUM UVIS2-C1 F606W none none none none 2 841.0 S S K1C-CTE FRB20220610A 5 WFC3/UVI ACCUM UVIS2-C1 F606W none none none none 2 841.0 S S K1C-CTE FRB20220610A 6 WFC3/UVI ACCUM UVIS2-C1 F606W none none none none 2 841.0 S S K1C-CTE 17277( 2) - 09-Dec-2022 16:01:28 - [ 5] Visit: 02 Visit Requirements: ORIENT -5D TO 5D FROM 01 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 FRB20220610 WFC3/IR MULTIAC IR F160W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF POS TARG -55, -45 A CUM (602.938 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 FRB20220610 WFC3/IR MULTIAC IR F160W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF POS TARG -52.9180, A CUM (602.938 -44.8600 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 FRB20220610 WFC3/IR MULTIAC IR F160W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF POS TARG -50.8360, A CUM (602.938 -44.7150 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 FRB20220610 WFC3/IR MULTIAC IR F160W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF POS TARG -54.8470, A CUM (602.938 -43.1400 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 FRB20220610 WFC3/IR MULTIAC IR F160W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF POS TARG -52.7650, A CUM (602.938 -42.9960 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 FRB20220610 WFC3/IR MULTIAC IR F160W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF POS TARG -50.6800, A CUM (602.938 -42.8520 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 FRB20220610 WFC3/IR MULTIAC IR F160W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF POS TARG -53.8810, A CUM (602.938 -41.2740 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 FRB20220610 WFC3/IR MULTIAC IR F160W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF POS TARG -51.7990, A CUM (602.938 -41.1330 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 | ------------------------------------------------------------------------------------------------------------------------------------ FRB20220610A 1 WFC3/IR MULTIAC IR F160W none none none none 1 N/A CUM FRB20220610A 2 WFC3/IR MULTIAC IR F160W none none none none 1 N/A CUM 17277( 2) - 09-Dec-2022 16:01:28 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ FRB20220610A 3 WFC3/IR MULTIAC IR F160W none none none none 1 N/A CUM FRB20220610A 4 WFC3/IR MULTIAC IR F160W none none none none 1 N/A CUM FRB20220610A 5 WFC3/IR MULTIAC IR F160W none none none none 2 N/A CUM FRB20220610A 6 WFC3/IR MULTIAC IR F160W none none none none 2 N/A CUM FRB20220610A 7 WFC3/IR MULTIAC IR F160W none none none none 2 N/A CUM FRB20220610A 8 WFC3/IR MULTIAC IR F160W none none none none 2 N/A CUM 17277( 2) - 09-Dec-2022 16:01:28 - [ 7] Summary Form for Proposal 17277 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, UVIS2-C1K1C-CTE ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=13, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT -5D TO 5D FROM 01, POS TARG -50.6800, -42.8520, POS TARG -50.8360, -44.7150, POS TARG -51.7990, -41.1330, POS TARG -52.7650, -42.9960, POS TARG -52.9180, -44.8600, POS TARG -53.8810, -41.2740, POS TARG -54.8470, -43.1400, POS TARG -55, -45, POS TARG 0.4635, 1.6880, POS TARG 0.9255, 0.9890, POS TARG 1.1910, 2.5650, POS TARG 1.6525, 1.8660, POS TARG 2.5120, 2.5855 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W, F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names FRB20220610A ------------------------------------------------------------------------------------------------------------------------------------