17878( 3) - 25-Oct-2024 15:12:01 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17878 Version: 3 Check-in Time: 25-Oct-2024 15:12:01 STScI Edit Number: 0 Title Community Discovery Program: CXO/VLA/HST observations of GW-detected compact mergers in O4b ------------------------------------------------------------------------------------ Type Cycle GO 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Sergio Campana INAF, Osservatorio Astronomico di Brera, Y Merate CoI: Prof. Daryl Haggard McGill University Y ------------------------------------------------------------------------------------ Abstract Chandra was the first facility to detect X-ray light from a watershed neutron star (NS) merger. In this ToO program we propose to continue Chandra's legacy in the nascent and revolutionary field of gravitational wave astronomy to identify, monitor, and characterize X-ray emission from compact-object mergers. Our goals are three-fold: (i) to characterize the diversity of emission from NS-NS mergers; (ii) to enable breakthroughs, such as the discovery of emission from a neutron star-black hole (NS-BH) merger and (iii) to model panchromatic jetemission to constrain system parameters, particularly inclination and jet structure. We will support these Chandra observations via coordinated multi-wavelength follow-up, including with VLA (radio) and HST (optical). We have gathered a large, international team to maximize our scientific output during the second half of LIGO/Virgo/KAGRA's 4th Observing Run (O4b), expected to run from Apr 2024 to early 2025. To enhance the scientific impact of these data, their value to the community, and to fully engage junior scientists in this frontier scientific pursuit we also waive any proprietary rights. ------------------------------------------------------------------------------------ Observations Description ------------------------ Chandra Cyle 26: We request a companion HST observation for 3 Chandra/VLA epochs at 15-30 d, 100-150 d, and 200-300 d to constrain the spectral index and location of the cooling break. We select the F606W filter on the WFC3 due to its broadband sensitivity and continuity with ground-based r-band, which will enable a complete light curve out to late times. Based on Fig. 5, to probe jets with more optimistic densities (n~0.1 cm-3), we request our first HST observation to reach a 3sigma limiting mag of mF606W = 28 AB, coordinated with the 15-30 d epoch. We forgo the first Chandra observation as the kilonova emission will still be expected to dominate at < 1 week. Using the WFC3 ETC, this requires 3 orbits, assuming 40 min of usable time per orbit. To probe GW170817-like events which are fainter and peak on longer timescales, we request two deeper epochs to reach mF606W = 28.5 AB mag roughly coordinated with our 100-150 d and 200-300 d epochs. This requires 2x6 = 12 orbits. Chandra Cycle 25 follow-up: We request HST/WFC3 F606W observations aligned with two of the final three Chandra epochs, for a total of 2x6= 12 orbits to achieve detections or reasonable limits on this target. 17878( 3) - 25-Oct-2024 15:12:01 - [ 2] Galaxy Template: Finally, we note that the host galaxy of GW170817 had severe contamination which impacted the reliability of the counterpart photometry in the absence of a template. It is possible that the last epoch will serve as this template if a source is no longer detected. However, if the final epoch yields a detected source with S/N > 3, we request one additional 6-orbit epoch at t-t0 > 300 days to serve as a deep template and mitigate contamination, assuming only one of the events will need a template. Thus our total HST request is 33 orbits. ------------------------------------------------------------------------------------ 17878( 3) - 25-Oct-2024 15:12:01 - [ 3] TARGET LIST Generic Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Selection Criteria | Flux data No | Name | Description | | ------------------------------------------------------------------------------------------------------------------------------------ 1 GW-1 STAR, GAMMA RAY GW TRIGGER V = 28 BURSTER, NEUTRON STAR Comments: Electromagnetic counterpart of a GW trigger ------------------------------------------------------------------------------------------------------------------------------------ 2 GW-2 STAR, GAMMA RAY GW TRIGGER V = 28 BURSTER, NEUTRON STAR Comments: Electromagnetic counterpart of a GW trigger ------------------------------------------------------------------------------------------------------------------------------------ 17878( 3) - 25-Oct-2024 15:12:01 - [ 4] Visit: 01 (GW-1) Visit Requirements: TOO RESPONSE TIME 15.0D 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 GW-1 WFC3/UVI ACCUM UVIS F606W 3 2400 S POS TARG 0, 0 S see below (7851 S) Comments: TOO observation ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 1 none 1 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 2 none 2 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 3 none 3 2617.0 S S 17878( 3) - 25-Oct-2024 15:12:01 - [ 5] Visit: 02 (GW-1) Visit Requirements: TOO RESPONSE TIME 100.0D 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 GW-1 WFC3/UVI ACCUM UVIS F606W 6 2400 S S see below (15702 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 | ------------------------------------------------------------------------------------------------------------------------------------ GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 1 none 1 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 2 none 2 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 3 none 3 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 4 none 4 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 5 none 5 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 6 none 6 2617.0 S S 17878( 3) - 25-Oct-2024 15:12:01 - [ 6] Visit: 03 (GW-1) Visit Requirements: TOO RESPONSE TIME 200.0D 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 GW-1 WFC3/UVI ACCUM UVIS F606W 6 2400 S S see below (15702 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 | ------------------------------------------------------------------------------------------------------------------------------------ GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 1 none 1 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 2 none 2 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 3 none 3 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 4 none 4 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 5 none 5 2617.0 S S GW-1 1 WFC3/UVI ACCUM UVIS F606W none none 6 none 6 2617.0 S S 17878( 3) - 25-Oct-2024 15:12:01 - [ 7] Visit: 04 (GW-2) Visit Requirements: TOO RESPONSE TIME 100.0D 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 GW-2 WFC3/UVI ACCUM UVIS F606W 6 2400 S S see below (15702 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 | ------------------------------------------------------------------------------------------------------------------------------------ GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 1 none 1 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 2 none 2 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 3 none 3 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 4 none 4 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 5 none 5 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 6 none 6 2617.0 S S 17878( 3) - 25-Oct-2024 15:12:01 - [ 8] Visit: 05 (GW-2) Visit Requirements: TOO RESPONSE TIME 200.0D 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 GW-2 WFC3/UVI ACCUM UVIS F606W 6 2400 S S see below (15702 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 | ------------------------------------------------------------------------------------------------------------------------------------ GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 1 none 1 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 2 none 2 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 3 none 3 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 4 none 4 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 5 none 5 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 6 none 6 2617.0 S S 17878( 3) - 25-Oct-2024 15:12:01 - [ 9] Visit: 06 (GW-1) Visit Requirements: TOO RESPONSE TIME 300.0D 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 GW-2 WFC3/UVI ACCUM UVIS F606W 6 2400 S S see below (15702 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 | ------------------------------------------------------------------------------------------------------------------------------------ GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 1 none 1 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 2 none 2 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 3 none 3 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 4 none 4 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 5 none 5 2617.0 S S GW-2 1 WFC3/UVI ACCUM UVIS F606W none none 6 none 6 2617.0 S S 17878( 3) - 25-Oct-2024 15:12:01 - [ 10] Summary Form for Proposal 17878 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements POS TARG 0, 0, TOO RESPONSE TIME 100.0D, TOO RESPONSE TIME 15.0D, TOO RESPONSE TIME 200.0D, TOO RESPONSE TIME 300.0D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names GW-1, GW-2 ------------------------------------------------------------------------------------------------------------------------------------