15886( 2) - 26-Jul-2019 19:27:41 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15886 Version: 2 Check-in Time: 26-Jul-2019 19:27:41 STScI Edit Number: 0 Title 1000 Days of GW170817: A Deep Multi-Band View of the First Neutron Star Merger with HST ------------------------------------------------------------------------------------ Type Cycle GO 27 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Wen-fai Fong Northwestern University Y CoI: Prof. Edo Berger Harvard University N CoI: Dr. Raffaella Margutti Northwestern University N CoI: Dr. Kate Denham Alexander Northwestern University N CoI: Prof. Ryan Chornock Ohio University N CoI: Dr. K Paterson Northwestern University N CoI: Mr. Peter Blanchard Harvard University N ------------------------------------------------------------------------------------ Abstract The joint detection of gravitational waves and light from the binary neutron star merger GW170817 has ushered in a new era of discovery. HST has played a pivotal role in characterizing the optical and near-infrared (NIR) evolution of GW170817, with reported detections of the kilonova and afterglow spanning ~10-350 days post-merger. In particular, at >100 days, the afterglow brightness is extremely faint at >26 mag; thus all detections or constraining upper limits at late times were enabled by HST. One major complication in measuring accurate photometry of the faint optical and NIR afterglow is contaminating light from the host galaxy, which has complex morphological structure. The only way to properly address this issue is by re-visiting the field after the afterglow has faded to obtain deep multi-band template images, against which we can subtract earlier epochs. Motivated by a case study in one of the optical filters, here we propose 13 orbits of HST/WFC3 imaging to obtain late-time template images in four filters, comprising all filters which have HST imaging beyond ~100 days and for which no adequate template images exist. These images will enable reliable and uniform photometry of the optical/NIR afterglow to GW170817 for the first time. In conjunction with ongoing radio and X-ray campaigns by the community, this will allow accurate inferred properties of relativistic outflows from the merger, and the deepest limits on a star cluster at the merger position, strongly constraining the binary progenitor's formation. Given the high-impact nature of GW170817, we waive all proprietary rights associated with data from this proposal. ------------------------------------------------------------------------------------ Observations Description ------------------------ This proposal is for multi-wavelength observations of the optical counterpart of GW170817 with UVIS/F814W (3 orbits), WFC3/F110W (4 orbits), WFC3/F140W (3 orbits), and WFC3/F160W (3 orbits). These observations are for a template observation of the afterglow of GW170817 and the visits may occur at any point during the cycle. These filters and apertures have been purposely chosen to match those of previous observations of this source. We note that GW170817 is a point source on the outskirts of NGC4993, a bright S0 galaxy, and that the expected brightness of GW170817 is >28 mag. 15886( 2) - 26-Jul-2019 19:27:41 - [ 2] ------------------------------------------------------------------------------------ 15886( 2) - 26-Jul-2019 19:27:41 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GW170817 EXT-STAR, GAMMA RAY RA=13H09M48.0900S, J2000 V = 27 BURSTER DEC=-23D22'53.35" Reference Frame: Other: SIMBAD Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 15886( 2) - 26-Jul-2019 19:27:41 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 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 ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-LINE-3PT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.605 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 41.788 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.173 Line_Spacing 0.112 Coordinate_Frame POS-TARG Pattern_Orient 23.884 Angle_Between_Sides 81.785 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 4 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE-3PT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.135 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 15886( 2) - 26-Jul-2019 19:27:41 - [ 5] Visit: 01 Visit Requirements: ORIENT 345D TO 76 D; ORIENT 84D TO 164 D; ORIENT 174D TO 248 D; ORIENT 274D TO 326 D On Hold Comments: Additional Comments: 4-orbit observation with IR/F110W. We restrict the ORIENT ranges to avoid a bright star positioned at the edge of the chip (which has previously caused contamination in other observations). 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 GW170817 WFC3/IR MULTIAC IR F110W NSAMP=14, SAMP-SEQ=SPARS100 1 DEF PATTERN 1 1 CUM (5211.746 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 GW170817 WFC3/IR MULTIAC IR F110W NSAMP=14, SAMP-SEQ=SPARS100 1 DEF POS TARG 0.68, 0.61; CUM (5211.746 PATTERN 1 2 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 | ------------------------------------------------------------------------------------------------------------------------------------ GW170817 1 WFC3/IR MULTIAC IR F110W 1 none none none 1 N/A CUM GW170817 1 WFC3/IR MULTIAC IR F110W 2 none none none 1 N/A CUM GW170817 1 WFC3/IR MULTIAC IR F110W 3 none none none 2 N/A CUM GW170817 1 WFC3/IR MULTIAC IR F110W 4 none none none 2 N/A CUM GW170817 2 WFC3/IR MULTIAC IR F110W 1 none none none 3 N/A CUM GW170817 2 WFC3/IR MULTIAC IR F110W 2 none none none 3 N/A CUM GW170817 2 WFC3/IR MULTIAC IR F110W 3 none none none 4 N/A CUM GW170817 2 WFC3/IR MULTIAC IR F110W 4 none none none 4 N/A CUM 15886( 2) - 26-Jul-2019 19:27:41 - [ 6] Visit: 02 Visit Requirements: ORIENT 345D TO 76 D; ORIENT 84D TO 164 D; ORIENT 174D TO 248 D; ORIENT 274D TO 326 D On Hold Comments: Additional Comments: 3-orbit observation with IR/F140W. We restrict the ORIENT ranges to avoid a bright star positioned at the edge of the chip (which has previously caused contamination in other observations). We employ a small POS-TARG offset between dither patterns. We add a small exposure at the end of the visit to fill out the orbit. 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 GW170817 WFC3/IR MULTIAC IR F140W NSAMP=14, SAMP-SEQ=SPARS100 1 DEF POS TARG 0.67, 0.2; CUM (5211.746 PATTERN 1 1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 GW170817 WFC3/IR MULTIAC IR F140W NSAMP=9, SAMP-SEQ=SPARS100 1 DEF POS TARG 0.68, 0.61; CUM (2408.805 PATTERN 2 2 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 GW170817 WFC3/IR MULTIAC IR F140W NSAMP=9, SAMP-SEQ=SPARS25 1 DEF POS TARG 0.68, 0.61 CUM (202.936 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 | ------------------------------------------------------------------------------------------------------------------------------------ GW170817 1 WFC3/IR MULTIAC IR F140W 1 none none none 1 N/A CUM GW170817 1 WFC3/IR MULTIAC IR F140W 2 none none none 1 N/A CUM GW170817 1 WFC3/IR MULTIAC IR F140W 3 none none none 2 N/A CUM GW170817 1 WFC3/IR MULTIAC IR F140W 4 none none none 2 N/A CUM GW170817 2 WFC3/IR MULTIAC IR F140W 1 none none none 3 N/A CUM GW170817 2 WFC3/IR MULTIAC IR F140W 2 none none none 3 N/A CUM GW170817 2 WFC3/IR MULTIAC IR F140W 3 none none none 3 N/A CUM GW170817 3 WFC3/IR MULTIAC IR F140W none none none none 3 N/A CUM 15886( 2) - 26-Jul-2019 19:27:41 - [ 7] Visit: 03 Visit Requirements: ORIENT 345D TO 76 D; ORIENT 84D TO 164 D; ORIENT 174D TO 248 D; ORIENT 274D TO 326 D On Hold Comments: Additional Comments: 3-orbit observation with IR/F160W. We restrict the ORIENT ranges to avoid a bright star positioned at the edge of the chip (which has previously caused contamination in other observations). We employ a small POS-TARG offset between dither patterns. We add a small exposure at the end of the visit to fill out the orbit. 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 GW170817 WFC3/IR MULTIAC IR F160W NSAMP=14, SAMP-SEQ=SPARS100 1 DEF PATTERN 1 1 CUM (5211.746 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 GW170817 WFC3/IR MULTIAC IR F160W NSAMP=9, SAMP-SEQ=SPARS100 1 DEF POS TARG 0.68, 0.61; CUM (2408.805 PATTERN 2 2 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 GW170817 WFC3/IR MULTIAC IR F160W NSAMP=9, SAMP-SEQ=SPARS25 1 DEF POS TARG 0.68, 0.61 CUM (202.936 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 | ------------------------------------------------------------------------------------------------------------------------------------ GW170817 1 WFC3/IR MULTIAC IR F160W 1 none none none 1 N/A CUM GW170817 1 WFC3/IR MULTIAC IR F160W 2 none none none 1 N/A CUM GW170817 1 WFC3/IR MULTIAC IR F160W 3 none none none 2 N/A CUM GW170817 1 WFC3/IR MULTIAC IR F160W 4 none none none 2 N/A CUM GW170817 2 WFC3/IR MULTIAC IR F160W 1 none none none 3 N/A CUM GW170817 2 WFC3/IR MULTIAC IR F160W 2 none none none 3 N/A CUM GW170817 2 WFC3/IR MULTIAC IR F160W 3 none none none 3 N/A CUM GW170817 3 WFC3/IR MULTIAC IR F160W none none none none 3 N/A CUM 15886( 2) - 26-Jul-2019 19:27:41 - [ 8] Visit: 04 Visit Requirements: ORIENT 338D TO 81 D; ORIENT 150D TO 265 D; ORIENT 287D TO 318 D On Hold Comments: Additional Comments: 3-orbit observation with UVIS/F814W. We restrict the ORIENT ranges to avoid a bright star positioned at the edge of the chip (which has previously caused contamination in other observations). 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 GW170817 WFC3/UVI ACCUM UVIS2 F814W 1 1340 S PATTERN 3 1 S (5360 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 GW170817 WFC3/UVI ACCUM UVIS2 F814W 1 860 S POS TARG 0.68, 0.21; S (2580 S) PATTERN 4 2 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GW170817 1 WFC3/UVI ACCUM UVIS2 F814W 1 none none none 1 N/A S GW170817 1 WFC3/UVI ACCUM UVIS2 F814W 2 none none none 1 N/A S GW170817 1 WFC3/UVI ACCUM UVIS2 F814W 3 none none none 2 N/A S GW170817 1 WFC3/UVI ACCUM UVIS2 F814W 4 none none none 2 N/A S GW170817 2 WFC3/UVI ACCUM UVIS2 F814W 1 none none none 3 N/A S GW170817 2 WFC3/UVI ACCUM UVIS2 F814W 2 none none none 3 N/A S GW170817 2 WFC3/UVI ACCUM UVIS2 F814W 3 none none none 3 N/A S 15886( 2) - 26-Jul-2019 19:27:41 - [ 9] Summary Form for Proposal 15886 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=14, NSAMP=9, SAMP-SEQ=SPARS100, SAMP-SEQ=SPARS25 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 150D TO 265 D, ORIENT 174D TO 248 D, ORIENT 274D TO 326 D, ORIENT 287D TO 318 D, ORIENT 338D TO 81 D, ORIENT 345D TO 76 D, ORIENT 84D TO 164 D, PATTERN 1 1, PATTERN 1 2, PATTERN 2 2, PATTERN 3 1, PATTERN 4 2, POS TARG 0.67, 0.2, POS TARG 0.68, 0.21, POS TARG 0.68, 0.61 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W, F140W, F160W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names GW170817 ------------------------------------------------------------------------------------------------------------------------------------