16911( 5) - 28-Feb-2022 19:08:50 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16911 Version: 5 Check-in Time: 28-Feb-2022 19:08:50 STScI Edit Number: 2 Title The Host Galaxy and Environment of the Unusual Transient AT2022cmc ------------------------------------------------------------------------------------ Type Cycle GO/DD 29 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Stephen Bradley Cenko NASA Goddard Space Flight Center Y CoI: Igor Andreoni NASA Goddard Space Flight Center N CoI: Dr. Daniel Perley Liverpool John Moores University N CoI: Anna Yen Qin Ho University of California - Berkeley N CoI: Dr. Mansi Kasliwal California Institute of Technology N CoI: Tomas Ahumada University of Maryland N CoI: Ms. Yuhan Yao California Institute of Technology N CoI: Erica Hammerstein University of Maryland N CoI: Dr. Suvi Gezari Space Telescope Science Institute N CoI: Prof. Varun Bhalerao Indian Institute of Technology Bombay N CoI: Dr. Dheeraj Pasham Massachusetts Institute of Technology N CoI: Dr. Michael W. Coughlin University of Minnesota - Twin Cities N ------------------------------------------------------------------------------------ Abstract AT2022cmc is a luminous, fast transient recently discovered by the Zwicky Transient Facility (ZTF). The combination of luminous (absolute magnitude -25), rapidly fading optical emission, extremely luminous (> 1e47 erg/s) X-ray emission, and self-absorbed radio emission, do not neatly fit into the traditional transient classification scheme. We consider the most likely explanations for AT2022cmc is either a relativistic tidal disruption event (i.e., a star disrupted by a central supermassive black hole that forms a new relativistic jet pointed along the observer line of sight), or an exceptional member of the new class of fast blue optical transients (FBOTs). Here we request HST observations to allow us to precisely pinpoint the transient location with respect to the host galaxy nucleus. A nuclear origin would strongly favor a relativistic tidal disruption event origin, only the fourth firmly established member of this class (and the first in over a decade). Alternatively, an off-nuclear origin would rule out a tidal disruption event, and instead favor either an exceptionally luminous FBOT or an entirely new class of transient phenomena. ------------------------------------------------------------------------------------ Observations Description ------------------------ AT2022cmc is a luminous, fast transient recently discovered by the Zwicky Transient Facility (ZTF). The combination of luminous (absolute magnitude -25), rapidly fading optical emission, extremely luminous (> 1e47 erg/s) X-ray emission, and self-absorbed radio emission, do not neatly fit into the traditional transient classification scheme. We consider the most likely explanations for AT2022cmc is either a relativistic tidal disruption event (i.e., a star disrupted by a central supermassive black hole that forms a new relativistic jet pointed along the observer line of sight), or an exceptional member of the new class of fast blue optical transients (FBOTs). Here we 16911( 5) - 28-Feb-2022 19:08:50 - [ 2] request HST observations to allow us to precisely pinpoint the transient location with respect to the host galaxy nucleus. A nuclear origin would strongly favor a relativistic tidal disruption event origin, only the fourth firmly established member of this class (and the first in over a decade). Alternatively, an off-nuclear origin would rule out a tidal disruption event, and instead favor either an exceptionally luminous FBOT or an entirely new class of transient phenomena. ------------------------------------------------------------------------------------ 16911( 5) - 28-Feb-2022 19:08:50 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AT2022CMC EXT-STAR, ACCRETION RA=13H34M43.2030S +/- 0.3", J2000 V = 22.0 +/- 0.2 DISK, NUCLEUS, X-RAY DEC=+33D13'0.67" +/- 0.3" TRANSIENT Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 16911( 5) - 28-Feb-2022 19:08:50 - [ 4] 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 ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-LINE-3PT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 1.210 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 41.788 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 16911( 5) - 28-Feb-2022 19:08:50 - [ 5] Visit: 01 Visit Requirements: BETWEEN 27-FEB-2022:00:00:00 AND 12-MAR-2022:00:00:00 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 AT2022CMC WFC3/UVI ACCUM UVIS F606W FLASH=5.0 1 348 S PATTERN 1 1 S (1044 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2022CMC WFC3/IR MULTIAC IR F160W NSAMP=15, SAMP-SEQ=SPARS25 1 DEF PATTERN 2 2 CUM (1058.819 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2022CMC 1 WFC3/UVI ACCUM UVIS F606W 1 none none none 1 N/A S AT2022CMC 1 WFC3/UVI ACCUM UVIS F606W 2 none none none 1 N/A S AT2022CMC 1 WFC3/UVI ACCUM UVIS F606W 3 none none none 1 N/A S AT2022CMC 2 WFC3/IR MULTIAC IR F160W 1 none none none 1 N/A CUM AT2022CMC 2 WFC3/IR MULTIAC IR F160W 2 none none none 1 N/A CUM AT2022CMC 2 WFC3/IR MULTIAC IR F160W 3 none none none 1 N/A CUM 16911( 5) - 28-Feb-2022 19:08:50 - [ 6] Visit: 02 Visit Requirements: AFTER 01 BY 120 D TO 240 D 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 AT2022CMC WFC3/UVI ACCUM UVIS F606W 1 800 S GS ACQ SCENARIO BASE1BE; S (2400 S) PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2022CMC WFC3/IR MULTIAC IR F160W SAMP-SEQ=SPARS100, NSAMP=9 1 DEF PATTERN 2 2 CUM (2408.805 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2022CMC 1 WFC3/UVI ACCUM UVIS F606W 1 none none none 1 N/A S AT2022CMC 1 WFC3/UVI ACCUM UVIS F606W 2 none none none 1 N/A S AT2022CMC 1 WFC3/UVI ACCUM UVIS F606W 3 none none none 1 N/A S AT2022CMC 2 WFC3/IR MULTIAC IR F160W 1 none none none 2 N/A CUM AT2022CMC 2 WFC3/IR MULTIAC IR F160W 2 none none none 2 N/A CUM AT2022CMC 2 WFC3/IR MULTIAC IR F160W 3 none none none 2 N/A CUM 16911( 5) - 28-Feb-2022 19:08:50 - [ 7] Summary Form for Proposal 16911 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, UVIS ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=5.0, NSAMP=15, NSAMP=9, SAMP-SEQ=SPARS100, SAMP-SEQ=SPARS25 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 120 D TO 240 D, BETWEEN 27-FEB-2022:00:00:00 AND 12-MAR-2022:00:00:00, GS ACQ SCENARIO BASE1BE, PATTERN 1 1, PATTERN 2 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W, F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names AT2022CMC ------------------------------------------------------------------------------------------------------------------------------------