17611( 8) - 22-Oct-2025 12:53:46 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17611 Version: 8 Check-in Time: 22-Oct-2025 12:53:46 STScI Edit Number: 3 Title Measuring the Hubble constant with the next multiple-imaged lensed supernova ------------------------------------------------------------------------------------ Type Cycle GO 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Ariel Goobar Stockholm University Y CoI: Dr. Nikki Arendse Stockholm University N CoI: Dr. Suhail Dhawan University of Cambridge N CoI: Prof. Edvard Mortsell Stockholm University N CoI: Dr. Joel Pearson Johansson Stockholm University N CoI: Dr. Lin Yan California Institute of Technology N CoI: Dr. Jakob Nordin Humboldt Universitat zu Berlin N CoI: Ana Sagues Carracedo Stockholm University N CoI: Dr. Christoffer Fremling California Institute of Technology N CoI: Dr. Mickael Rigault Institut des deux Infinis de Lyon N CoI: Dr. Mathew Smith Institut des deux Infinis de Lyon N CoI: Dr. Angela Adamo Stockholm University N CoI: Dr. Adelaide Marie Claeyssens Centre de Recherche Astrophysique de Lyon N CoI: Dr. T. Emil Rivera-Thorsen Stockholm University N CoI: Ms. Alice Townsend Humboldt Universitat zu Berlin N CoI: Dr. Stephen Thorp Stockholm University N CoI: Mr. William D'Arcy Kenworthy Stockholm University N CoI: Igor Andreoni University of North Carolina at Chapel N Hill CoI: Dr. Peter E. Nugent Lawrence Berkeley National Laboratory N CoI: Dr. Thomas E. Collett University of Portsmouth N CoI: Prof. Graham Smith University of Birmingham N ------------------------------------------------------------------------------------ Abstract Spectroscopic time-delay measurements of multiply-imaged supernovae offer a very efficient way to measure the expansion rate of the universe. NIRCam and NIRSpec follow-up observations with JWST upon the next lensed supernova (SN) discovered by the Zwicky Transient Facility (ZTF) or the La Silla Schmidt Southern Survey (LS4) could pave the way for a novel technique to measure the Hubble constant and adress the "Hubble tension". Unlike any other time-delay measurement, spectroscopic dating of multiple SN images can be done without repeated observations. We propose to select a suitable lensed supernova for ToO observations and anticipate a 5% (or better) measurement of H0, with only 3.5 hours of JWST time. ------------------------------------------------------------------------------------ Observations Description ------------------------ Target of opportunity imaging observations of a confirmed lensed SN. Three optical filters and one NIR. ------------------------------------------------------------------------------------ 17611( 8) - 22-Oct-2025 12:53:46 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2025WNY STAR, GRAVITATIONAL RA=07H16M34.5000S +/- 0.01", J2000 V = 20 +/- 0.5 LENS, SUPERNOVA DEC=+38D21'7.76" +/- 0.01" Reference Frame: ICRS Comments: Transient in the ZTF survey in a known galaxy-scale lensing candidate system (lens at z=0.3754) . Liverpool telescope images from Oct 3 and 4 revelaled two additional fainter images, indicating the lensing nature of the transient. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17611( 8) - 22-Oct-2025 12:53:46 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-LINE-3PT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 1.305 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 41.788 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 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 ------------------------------------------------------------------------------------------------------------------------------------ 17611( 8) - 22-Oct-2025 12:53:46 - [ 4] Visit: 01 (Epoch 1) Visit Requirements: SCHED 100%; ON HOLD ; TOO RESPONSE TIME 21.0D On Hold Comments: This is a generic target in ToO mode 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 AT2025WNY WFC3/UVI ACCUM UVIS2-C51 F475W FLASH=14 1 42 S PATTERN 2 1 S 2C-SUB see below (591 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2025WNY WFC3/UVI ACCUM UVIS2-C51 F625W FLASH=14 1 13 S PATTERN 2 2 S 2C-SUB see below (252 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 AT2025WNY WFC3/UVI ACCUM UVIS2-C51 F814W FLASH=14 1 20 S PATTERN 2 3 S 2C-SUB see below (273 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 AT2025WNY WFC3/IR MULTIAC IRSUB512 F160W NSAMP=10, SAMP-SEQ=SPARS25 1 DEF POS TARG null, 10; CUM (621.433 PATTERN 1 4 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2025WNY 1 WFC3/UVI ACCUM UVIS2-C5 F475W 1 none none none 1 197.0 S S 12C-SUB AT2025WNY 1 WFC3/UVI ACCUM UVIS2-C5 F475W 2 none none none 1 197.0 S S 12C-SUB AT2025WNY 1 WFC3/UVI ACCUM UVIS2-C5 F475W 3 none none none 1 197.0 S S 12C-SUB AT2025WNY 2 WFC3/UVI ACCUM UVIS2-C5 F625W 1 none none none 1 84.0 S S 12C-SUB AT2025WNY 2 WFC3/UVI ACCUM UVIS2-C5 F625W 2 none none none 1 84.0 S S 12C-SUB AT2025WNY 2 WFC3/UVI ACCUM UVIS2-C5 F625W 3 none none none 1 84.0 S S 12C-SUB AT2025WNY 3 WFC3/UVI ACCUM UVIS2-C5 F814W 1 none none none 1 91.0 S S 12C-SUB AT2025WNY 3 WFC3/UVI ACCUM UVIS2-C5 F814W 2 none none none 1 91.0 S S 12C-SUB AT2025WNY 3 WFC3/UVI ACCUM UVIS2-C5 F814W 3 none none none 1 91.0 S S 12C-SUB AT2025WNY 4 WFC3/IR MULTIAC IRSUB512 F160W 1 none none none 1 N/A CUM 17611( 8) - 22-Oct-2025 12:53:46 - [ 5] 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2025WNY 4 WFC3/IR MULTIAC IRSUB512 F160W 2 none none none 1 N/A CUM AT2025WNY 4 WFC3/IR MULTIAC IRSUB512 F160W 3 none none none 1 N/A CUM 17611( 8) - 22-Oct-2025 12:53:46 - [ 6] Visit: 02 (Epoch 2) Visit Requirements: SCHED 100%; AFTER 01 BY 40 D TO 53 D; ON HOLD ; TOO RESPONSE TIME 21.0D On Hold Comments: This is a generic target in ToO mode 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 AT2025WNY WFC3/UVI ACCUM UVIS2-C51 F475W FLASH=14 1 42 S PATTERN 2 1 S 2C-SUB see below (591 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2025WNY WFC3/UVI ACCUM UVIS2-C51 F625W FLASH=14 1 13 S PATTERN 2 2 S 2C-SUB see below (252 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 AT2025WNY WFC3/UVI ACCUM UVIS2-C51 F814W FLASH=14 1 20 S PATTERN 2 3 S 2C-SUB see below (273 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 AT2025WNY WFC3/IR MULTIAC IRSUB512 F160W NSAMP=10, SAMP-SEQ=SPARS25 1 DEF POS TARG null, 10; CUM (621.433 PATTERN 1 4 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2025WNY 1 WFC3/UVI ACCUM UVIS2-C5 F475W 1 none none none 1 197.0 S S 12C-SUB AT2025WNY 1 WFC3/UVI ACCUM UVIS2-C5 F475W 2 none none none 1 197.0 S S 12C-SUB AT2025WNY 1 WFC3/UVI ACCUM UVIS2-C5 F475W 3 none none none 1 197.0 S S 12C-SUB AT2025WNY 2 WFC3/UVI ACCUM UVIS2-C5 F625W 1 none none none 1 84.0 S S 12C-SUB AT2025WNY 2 WFC3/UVI ACCUM UVIS2-C5 F625W 2 none none none 1 84.0 S S 12C-SUB AT2025WNY 2 WFC3/UVI ACCUM UVIS2-C5 F625W 3 none none none 1 84.0 S S 12C-SUB AT2025WNY 3 WFC3/UVI ACCUM UVIS2-C5 F814W 1 none none none 1 91.0 S S 12C-SUB AT2025WNY 3 WFC3/UVI ACCUM UVIS2-C5 F814W 2 none none none 1 91.0 S S 12C-SUB AT2025WNY 3 WFC3/UVI ACCUM UVIS2-C5 F814W 3 none none none 1 91.0 S S 12C-SUB AT2025WNY 4 WFC3/IR MULTIAC IRSUB512 F160W 1 none none none 1 N/A CUM 17611( 8) - 22-Oct-2025 12:53:46 - [ 7] 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2025WNY 4 WFC3/IR MULTIAC IRSUB512 F160W 2 none none none 1 N/A CUM AT2025WNY 4 WFC3/IR MULTIAC IRSUB512 F160W 3 none none none 1 N/A CUM 17611( 8) - 22-Oct-2025 12:53:46 - [ 8] Summary Form for Proposal 17611 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IRSUB512, UVIS2-C512C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=14, NSAMP=10, SAMP-SEQ=SPARS25 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 40 D TO 53 D, ON HOLD , PATTERN 1 4, PATTERN 2 1, PATTERN 2 2, PATTERN 2 3, POS TARG null, 10, SCHED 100%, TOO RESPONSE TIME 21.0D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W, F475W, F625W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names AT2025WNY ------------------------------------------------------------------------------------------------------------------------------------