16923( 2) - 13-Mar-2022 19:40:01 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16923 Version: 2 Check-in Time: 13-Mar-2022 19:40:01 STScI Edit Number: 0 Title Solidifying the Origin of a Possible Kilonova at 350 Mpc ------------------------------------------------------------------------------------ Type Cycle GO 29 ------------------------------------------------------------------------------------ Investigators Contact? PI: Jillian Rastinejad Northwestern University Y CoI: Prof. Andrew James Levan Radboud Universiteit Nijmegen N CoI: Dr. Wen-fai Fong Northwestern University N CoI: Dr. Benjamin Paul Gompertz The University of Warwick N CoI: Dr. Matt Nicholl University of Birmingham N CoI: Dr. Daniele Bjorn Malesani Radboud Universiteit Nijmegen N CoI: Dr. Gavin Lamb University of Leicester N CoI: Dr. Samantha Oates University of Birmingham N CoI: Dr. Charles Kilpatrick Northwestern University N CoI: Dr. Alicia Rouco Escorial Northwestern University N CoI: Anya Elizabeth Nugent Northwestern University N CoI: Prof. Nial Rahil Tanvir University of Leicester N CoI: Genevieve Schroeder Northwestern University N ------------------------------------------------------------------------------------ Abstract Neutron star mergers are confirmed sites of r-process nucleosynthesis, observationally identified by their kilonovae. In particular, the study of short gamma-ray bursts (SGRBs), which span z~0.1-2, are a promising avenue to uncover kilonovae. Monitoring the temporal and color evolution of SGRB-kilonovae provides quantifiable estimates of their ejecta masses and compositions, of interest to assessing the contribution of such mergers to the universe's heavy element budget. In particular, the identification of nearby (z<0.1) kilonovae provide great distinguishing power. Recently, GRB 211211A was discovered in likely association with a galaxy at 350 Mpc (z=0.076). At this distance, the detection and temporal behavior of an associated NIR transient is fully consistent with a kilonova. If the distance is confirmed, this would make GRB 211211A the most nearby such event beyond the multi-messenger GW170817. We propose 2 orbits of HST imaging to secure the nearby origin of GRB 211211A by placing constraints on an underlying, unseen galaxy. Current ground-based observations have reached their limits, and cannot rule out the full range of known host galaxy luminosities and redshifts. If an underlying galaxy is detected from a higher-redshift origin, the NIR transient would be equally exciting, outshining any known kilonova or supernova to date. ------------------------------------------------------------------------------------ Observations Description ------------------------ This proposal is for 2 orbits of imaging at the position of the afterglow of GRB 211211A with ACS/WFC/F606W (1 orbit) and WFC3/IR/F140W (1 orbit). These observations are to place deep constraints on an underlying host galaxy and to calculate a precise offset between the counterpart and the center of the host galaxy. The expected brightness of the afterglow is > 28 mag. The putative host galaxy is r = 19.8 AB mag. 16923( 2) - 13-Mar-2022 19:40:01 - [ 2] ------------------------------------------------------------------------------------ 16923( 2) - 13-Mar-2022 19:40:01 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GRB211211A EXT-STAR, GAMMA RAY RA=14H09M10.0898S, J2000 V = 27.0 BURSTER, NEUTRON STAR DEC=+27D53'20.66" Reference Frame: Other: SDSS ------------------------------------------------------------------------------------------------------------------------------------ 16923( 2) - 13-Mar-2022 19:40:01 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.262 Line_Spacing 0.192 Coordinate_Frame POS-TARG Pattern_Orient 18.39 Angle_Between_Sides 68.14 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.572 Line_Spacing 0.365 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 16923( 2) - 13-Mar-2022 19:40:01 - [ 5] Visit: 01 (optical) Visit Requirements: ORIENT 165D TO 145 D; BEFORE 31-MAY-2022:00:00:00 On Hold Comments: Additional Comments: 1-orbit observation with ACS/WFC/F606W. 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 GRB211211A ACS/WFC ACCUM WFC1-CTE F606W 1 500 S POS TARG -20, -21; (2000 S) 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 | ------------------------------------------------------------------------------------------------------------------------------------ GRB211211A 1 ACS/WFC ACCUM WFC1-CTE F606W 1 none none none 1 N/A GRB211211A 1 ACS/WFC ACCUM WFC1-CTE F606W 2 none none none 1 N/A GRB211211A 1 ACS/WFC ACCUM WFC1-CTE F606W 3 none none none 1 N/A GRB211211A 1 ACS/WFC ACCUM WFC1-CTE F606W 4 none none none 1 N/A 16923( 2) - 13-Mar-2022 19:40:01 - [ 6] Visit: 02 (near-IR) Visit Requirements: ORIENT 165D TO 145 D; BEFORE 31-MAY-2022:00:00:00 On Hold Comments: Additional Comments: 1-orbit observation with WFC3/IR/F140W. 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 GRB211211A WFC3/IR MULTIAC IR F140W NSAMP=7, SAMP-SEQ=SPARS100 1 DEF PATTERN 3 1 CUM (2411.737 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 | ------------------------------------------------------------------------------------------------------------------------------------ GRB211211A 1 WFC3/IR MULTIAC IR F140W 1 none none none 1 N/A CUM GRB211211A 1 WFC3/IR MULTIAC IR F140W 2 none none none 1 N/A CUM GRB211211A 1 WFC3/IR MULTIAC IR F140W 3 none none none 1 N/A CUM GRB211211A 1 WFC3/IR MULTIAC IR F140W 4 none none none 1 N/A CUM 16923( 2) - 13-Mar-2022 19:40:01 - [ 7] Summary Form for Proposal 16923 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, WFC1-CTE ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=7, SAMP-SEQ=SPARS100 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BEFORE 31-MAY-2022:00:00:00, ORIENT 165D TO 145 D, PATTERN 1 1, PATTERN 3 1, POS TARG -20, -21 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F140W, F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names GRB211211A ------------------------------------------------------------------------------------------------------------------------------------