0 Assigned ID: 2711 ----- Attempting Submission 1 (Mon Feb 21 03:03:27 GMT 2022) ----- Increased dither size in IR to improve photometric precision. -798367108 ----- Attempting Submission 1 (Mon Feb 28 01:29:16 GMT 2022) ----- ----- Attempting Submission 2 (Mon Feb 28 18:58:24 GMT 2022) ----- The Host Galaxy and Environment of the Unusual Transient AT2022cmc 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. 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. N/A. Supermassive Black Holes and Active Galaxies Stellar Physics and Stellar Types 0 false SUPPORTED EXT-STAR ACCRETION DISK NUCLEUS X-RAY TRANSIENT J2000 J2000 WFC3/UVIS Imaging No No F606W WFC3/IR Imaging No No F160W WFC3/UVIS Imaging No No F606W WFC3/IR Imaging No No F160W POS-TARG DITHER 0.135 LINE false false 3 46.84 WFC3-UVIS-DITHER-LINE-3PT 1 false POS-TARG DITHER 1.210 LINE false false 3 41.788 WFC3-IR-DITHER-LINE-3PT 2 false /private/var/folders/gz/3lhy64wd4yd94ffrdc3j3kjh41xjtg/T/OPVisit9222777436022457754.xml Timing link suitability includes constraints ([02 After 01 by 120.0 to 240.0 days]) The scheduling data was generated by CASM 30.1. CASM was run in Phase II mode. 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(Tic-Visit :proposal-id 16911 :visit-id "02" :proposal-version -1 :trans-version "20211222" :date "28-Feb-2022 13:22:10.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1388496 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16911 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16911 :visit-id "02" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2664 :al-overhead-at-end 116 :internal-dur-at-end 31 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3180 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16911 :visit-id "02" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2575 :al-overhead-at-end 0 :internal-dur-at-end 557 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3180 :pcs-gap 0 ) true 2 0