17238( 7) - 31-May-2023 20:21:39 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17238 Version: 7 Check-in Time: 31-May-2023 20:21:39 STScI Edit Number: 0 Title Comprehensive Chandra, Gemini, JVLA and HST observations of a fast blue optical transient ------------------------------------------------------------------------------------ Type Cycle GO 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Ashley Chrimes Radboud Universiteit Nijmegen Y CoI: Prof. Peter G. Jonker Radboud Universiteit Nijmegen N CoI: Prof. Andrew James Levan Radboud Universiteit Nijmegen N CoI: Prof. Paul J. Groot Radboud Universiteit Nijmegen N CoI: Dr. James Miller-Jones Curtin University N CoI: Dr. Elizabeth R. Stanway The University of Warwick N ------------------------------------------------------------------------------------ Abstract Fast blue optical transients (FBOTs) are a poorly understood class of extragalactic transient. They are at odds with being radioactively powered due to their rapid rise and fall timescales, and are very blue, indicating a high photospheric temperature. Faint FBOTs are now routinely detected, but bright, local events are rare. Only four were followed up with X-ray, optical spectroscopic, and radio observations in the last four years, of which only two had early time multi-wavelength observations. We propose a ToO joint programme (with Chandra, Gemini, JVLA and HST) to follow-up a single bright FBOT in detail. Our proposal will help to discern which features all FBOTs have in common, and will put strong constraints on the nature of the central engine and emission mechanisms. ------------------------------------------------------------------------------------ Observations Description ------------------------ These are target-of-oppourtunity observations of a new fast blue optical transients, spanning two epochs. For epoch (visit) 1: one orbit, consisting of a 1100s observation (with 3-point dither) in F555W, and a 1100s observation (with 3-point dither) in F814W. These observations will be triggered as a non-disruptive ToO, to be excuted within a few weeks of the initial transient detection. The observations will reach reach 3 sigma depths of F555W=27.3 and F814W=26.7 (AB). For epoch (visit) 2: three orbits. All triggered as a non-disruptive ToO, several months after epoch 1. Orbit 1: identical observations to the single orbit of epoch 1, for the purposes of difference imaging and precise transient localisation. Orbit 2: UV observations in F225W and F336W (1100s each, with 3-point dithers). The depths for these observations will be F225W=25.8 and F336W=26.2. These observations will constrain the prescence of high-mass stars at the transient location. Orbit 3: Observations (again totalling 2200s) with a narrow band, and off-band comparison filter, targeting Halpha, to measure the equivalent width of Halpha at the transient location. Because the transient redshift is unknown in 17238( 7) - 31-May-2023 20:21:39 - [ 2] advance, we cannot pre-determine the narrow band filter required to capture Halpha. ------------------------------------------------------------------------------------ 17238( 7) - 31-May-2023 20:21:39 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2023FHN STAR, SUPERNOVA RA=10H08M3.8150S, J2000 V = 24 DEC=+21D04'26.95" Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 17238( 7) - 31-May-2023 20:21:39 - [ 4] TARGET LIST Generic Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Selection Criteria | Flux data No | Name | Description | | ------------------------------------------------------------------------------------------------------------------------------------ 1 FBOT1 EXT-STAR, SUPERNOVA NEWLY DISCOVERED FBOT V = 21 +/- 3 ------------------------------------------------------------------------------------------------------------------------------------ 17238( 7) - 31-May-2023 20:21:39 - [ 5] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 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 ------------------------------------------------------------------------------------------------------------------------------------ 17238( 7) - 31-May-2023 20:21:39 - [ 6] Visit: 01 (Epoch 1 (F555W, F814W only)) Visit Requirements: ON HOLD ; TOO RESPONSE TIME 25.0D On Hold Comments: Awaiting FBOT trigger 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 AT2023FHN WFC3/UVI ACCUM UVIS2-C1K F555W FLASH=11 1 364 S PATTERN 1 1 S 1C-SUB (1092 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2023FHN WFC3/UVI ACCUM UVIS2-C1K F814W FLASH=11 1 364 S PATTERN 1 2 S 1C-CTE (1092 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2023FHN 1 WFC3/UVI ACCUM UVIS2-C1 F555W 1 none none none 1 N/A S K1C-SUB AT2023FHN 1 WFC3/UVI ACCUM UVIS2-C1 F555W 2 none none none 1 N/A S K1C-SUB AT2023FHN 1 WFC3/UVI ACCUM UVIS2-C1 F555W 3 none none none 1 N/A S K1C-SUB AT2023FHN 2 WFC3/UVI ACCUM UVIS2-C1 F814W 1 none none none 1 N/A S K1C-CTE AT2023FHN 2 WFC3/UVI ACCUM UVIS2-C1 F814W 2 none none none 1 N/A S K1C-CTE AT2023FHN 2 WFC3/UVI ACCUM UVIS2-C1 F814W 3 none none none 1 N/A S K1C-CTE 17238( 7) - 31-May-2023 20:21:39 - [ 7] Visit: 02 (Epoch 2) Visit Requirements: SCHED 70%; BETWEEN 01-OCT-2023:00:00:00 AND 31-DEC-2023:00:00:00; TOO RESPONSE TIME 25.0D 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 AT2023FHN WFC3/UVI ACCUM UVIS2-C1K F555W FLASH=11 1 330 S (990 PATTERN 1 1 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2023FHN WFC3/UVI ACCUM UVIS2-C1K F814W FLASH=11 1 364 S PATTERN 1 2 S 1C-CTE (1092 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 AT2023FHN WFC3/UVI ACCUM UVIS2-C1K F225W FLASH=16 1 356 S PATTERN 1 3 S 1C-SUB (1068 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 AT2023FHN WFC3/UVI ACCUM UVIS2-C1K F336W FLASH=16 1 356 S PATTERN 1 4 S 1C-SUB (1068 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 AT2023FHN WFC3/UVI ACCUM UVIS2-C1K F845M FLASH=14 1 330 S (990 PATTERN 1 5 S 1C-SUB S) Comments: Placeholder filter - to updated once the transient redshift is known, to target Halpha. ------------------------------------------------------------------------------------------------------------------------------------ 6 AT2023FHN WFC3/UVI ACCUM UVIS2-C1K F763M FLASH=13 1 356 S PATTERN 1 6 S 1C-CTE (1068 S) Comments: Placeholder filter - to updated once the transient redshift is known, to target Halpha. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2023FHN 1 WFC3/UVI ACCUM UVIS2-C1 F555W 1 none none none 1 N/A S K1C-SUB AT2023FHN 1 WFC3/UVI ACCUM UVIS2-C1 F555W 2 none none none 1 N/A S K1C-SUB AT2023FHN 1 WFC3/UVI ACCUM UVIS2-C1 F555W 3 none none none 1 N/A S K1C-SUB AT2023FHN 2 WFC3/UVI ACCUM UVIS2-C1 F814W 1 none none none 1 N/A S K1C-CTE AT2023FHN 2 WFC3/UVI ACCUM UVIS2-C1 F814W 2 none none none 1 N/A S K1C-CTE AT2023FHN 2 WFC3/UVI ACCUM UVIS2-C1 F814W 3 none none none 1 N/A S K1C-CTE 17238( 7) - 31-May-2023 20:21:39 - [ 8] 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2023FHN 3 WFC3/UVI ACCUM UVIS2-C1 F225W 1 none none none 2 N/A S K1C-SUB AT2023FHN 3 WFC3/UVI ACCUM UVIS2-C1 F225W 2 none none none 2 N/A S K1C-SUB AT2023FHN 3 WFC3/UVI ACCUM UVIS2-C1 F225W 3 none none none 2 N/A S K1C-SUB AT2023FHN 4 WFC3/UVI ACCUM UVIS2-C1 F336W 1 none none none 2 N/A S K1C-SUB AT2023FHN 4 WFC3/UVI ACCUM UVIS2-C1 F336W 2 none none none 2 N/A S K1C-SUB AT2023FHN 4 WFC3/UVI ACCUM UVIS2-C1 F336W 3 none none none 2 N/A S K1C-SUB AT2023FHN 5 WFC3/UVI ACCUM UVIS2-C1 F845M 1 none none none 3 N/A S K1C-SUB AT2023FHN 5 WFC3/UVI ACCUM UVIS2-C1 F845M 2 none none none 3 N/A S K1C-SUB AT2023FHN 5 WFC3/UVI ACCUM UVIS2-C1 F845M 3 none none none 3 N/A S K1C-SUB AT2023FHN 6 WFC3/UVI ACCUM UVIS2-C1 F763M 1 none none none 3 N/A S K1C-CTE AT2023FHN 6 WFC3/UVI ACCUM UVIS2-C1 F763M 2 none none none 3 N/A S K1C-CTE AT2023FHN 6 WFC3/UVI ACCUM UVIS2-C1 F763M 3 none none none 3 N/A S K1C-CTE 17238( 7) - 31-May-2023 20:21:39 - [ 9] Summary Form for Proposal 17238 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2-C1K1C-CTE, UVIS2-C1K1C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=11, FLASH=13, FLASH=14, FLASH=16 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-OCT-2023:00:00:00 AND 31-DEC-2023:00:00:00, ON HOLD , PATTERN 1 1, PATTERN 1 2, PATTERN 1 3, PATTERN 1 4, PATTERN 1 5, PATTERN 1 6, SCHED 70%, TOO RESPONSE TIME 25.0D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F225W, F336W, F555W, F763M, F814W, F845M ------------------------------------------------------------------------------------------------------------------------------------ Target Names AT2023FHN ------------------------------------------------------------------------------------------------------------------------------------