0 Assigned ID: 6366 ----- Attempting Submission 1 (Thu Apr 10 05:12:33 GMT 2025) ----- This target is not used in this proposal. This target is not used in this proposal. This pattern is not used in this proposal. This pattern is not used in this proposal. Sensitive exposures should have an ETC run number provided. Sensitive exposures should have an ETC run number provided. Sensitive exposures should have an ETC run number provided. Sensitive exposures should have an ETC run number provided. Submit to activate Visit 07 to observe the off-nuclear TDE 2023mfm. Four WFC3 imaging orbits approved under TTRBHST-93551. 1068571860 ----- Attempting Submission 1 (Mon Aug 11 21:35:25 GMT 2025) ----- ----- Attempting Submission 2 (Wed Nov 12 23:55:38 GMT 2025) ----- ----- Attempting Submission 3 (Thu Nov 13 23:34:55 GMT 2025) ----- ----- Attempting Submission 4 (Fri May 08 16:07:56 GMT 2026) ----- Not sure why it shows that "The Orbit Planner need to be run" and "The Visit Planner need to be run", because I have already run it. Please let me know if things need to be changed. Thanks! Unveiling Wandering Black Holes: HST Imaging and UV Spectroscopy of Off-nuclear Tidal Disruption Events The hierarchical assembly of galaxies and dynamical interactions in galactic nuclei naturally predict a population of off-nuclear massive black holes (MBHs), yet direct observational evidence remains limited. Off-nuclear tidal disruption events (TDEs) provide a unique avenue to probe these elusive wandering MBHs. We propose HST ToO observations of two offset TDE candidates selected with optical time-domain surveys. For each candidate, we request 1 orbit of WFC3 imaging and 4 orbits of SITS UV spectroscopy. The imaging will confirm the off-nuclear nature of the transient, precisely measure its offset from the host galaxy nucleus, and search for morphological signatures of recent mergers. The spectroscopic observations will constrain kick velocities and provide key diagnostics for this rare class of events. This program will increase the number of optically selected off-nuclear TDEs from one to three, enabling the first steps toward characterizing the demographics and physical origins of offset MBHs powering TDEs. This proposal consists of non-disruptive ToO observations (up to 25 days response time) of 2 off-nuclear tidal disruption events (TDEs), each for 5 orbits with HST. Each TDE trigger will be for an off-nculear TDE candidate that has (1) a peak g-band magnitude of <19.5, (2) a significant offset (>3-sigma) from the nearest galaxy nucleus determined via forward modeling of science images, and (3) an optical spectrum that is consistent with one of the established TDE classes: TDE+H, TDE+H+He, TDE+He, TDE-featureless. The 1 orbit of WFC3 imaging observation will be triggered if these three criteria are met. The 4 orbits of STIS spectroscopic observations will be triggered if the expected g-band magnitude is <20 mag. Due to the fact that the spectroscopic component will only be triggered if the predicted g<20, we have broken up each TDE trigger into 3 visits: first visit: 1 orbit with WFC3 imaging second visit: 2 orbits with STIS/FUV-MAMA using G140L with the 52x0.2 aperture third visit: 2 orbits with STIS/NUV-MAMA using G230L with the 52x0.2 aperture Each spectroscopic visit requires an ACQ in the first orbit. As these are triggered observations, we do not yet know the exact brightness of the TDE. We expect that the TDE will be a UV-bright point source that is offset from a (much redder) galaxy nucleus. Since the TDE is offset from the host, we have chosen nearby stars for aquisition observations, from which offsets will be applied to observe the TDEs. The exposure times may be adjusted depending on the actual properties of the target, so we have not provided ETC output until the actual fluxes are known. A ToO activation on TDE1 should trigger Visit 01, and also Visits 02 and 03 if the predicted g < 20. A ToO activation on TDE2 should trigger Visit 04, and also Visits 05 and 06 if the predicted g < 20. Dr. Yuhan Yao is a Miller postdoctoral fellow at UC Berkeley, specialized in using time domain surveys such as the Zwicky Transient Facility to select TDEs and multi-wavelength characterization of transients. She is the co-chair of the LS4 MBH science working group. She led the study on the first optically selected off-nuclear TDE AT2024tvd. Prof. Ryan Chornock is an expert on optical/UV observations of TDEs and other optical transients. He is the co-chair of the ZTF MBH Science Working Group. Prof. Raffaella Margutti is an associate professor at UC Berkeley. She is an expert of high-energy observations of transients. Prof. Wenbin Lu is an assistant professor at UC Berkeley. He is an expert in modeling the hydrodynamics of and radiation from TDEs. Dr. Charlotte Ward is a postdoctoral research associate at Princeton University. She has experience in finding off-nuclear AGN-powered transients and have developed forward modeling techniques for multi-epoch imaging of transient-host systems. Supermassive Black Holes and Active Galaxies Galaxies 6 false true false false false false false SUPPORTED UNIDENTIFIED ULTRAVIOLET EMITTER J2000 EXT-STAR M III-I NO J2000 UNIDENTIFIED ULTRAVIOLET EMITTER NO J2000 UNIDENTIFIED NUCLEUS ULTRAVIOLET EMITTER (1) spectroscopic TDE (2) >3-sigma offset from host galaxy center (3) g<19.5 UNIDENTIFIED NUCLEUS ULTRAVIOLET EMITTER (1) spectroscopic TDE (2) >3-sigma offset from host galaxy center (3) g<19.5 STAR UNDESIGNATED A star that is nearby TDE1 for acquisition STAR UNDESIGNATED A star that is nearby TDE2 for acquisition WFC3/UVIS Imaging No No F625W STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/FUV-MAMA Spectroscopic No No G140L 1425 WFC3/UVIS Imaging No No F625W STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/FUV-MAMA Spectroscopic No No G140L 1425 POS-TARG DITHER 0.135 LINE false false 3 46.84 WFC3-UVIS-DITHER-LINE-3PT 1 false POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 2 false POS-TARG DITHER 0.145 LINE false false 2 46.84 WFC3-UVIS-DITHER-LINE 3 false The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18131 :visit-id "01" :proposal-version -1 :trans-version "20250624" :date "12-Nov-2025 15:34:46.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 53488 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18131 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18131 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2592 :al-overhead-at-end 77 :internal-dur-at-end 95 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2976 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 33.1. 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CASM was run in Phase II mode. 1766425012000 37.0 (Tic-Visit :proposal-id 18131 :visit-id "03" :proposal-version -1 :trans-version "20250624" :date "13-Nov-2025 15:34:11.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 313504 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18131 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18131 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2596 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2976 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18131 :visit-id "03" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2596 :al-overhead-at-end 0 :internal-dur-at-end 582 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2976 :pcs-gap 0 ) false 2 0 The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. /Users/yuhanyao/Desktop/proposals/HST/HST_Cycle33/offset/OP-cache/2026-04-20-v04.xml (Tic-Visit :proposal-id 18131 :visit-id "04" :proposal-version -1 :trans-version "20250929" :date "20-Apr-2026 11:39:29.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 53488 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18131 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18131 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2438 :al-overhead-at-end 78 :internal-dur-at-end 95 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. 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CASM was run in Phase II mode. 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CASM was run in Phase II mode. - 1 orbit: WFC3/UVIS imaging in F625W - 1 orbit: WFC3/UVIS imaging in F225W - 1 orbit: WFC3/UVIS imaging in F275W - 1 orbit: WFC3/UVIS imaging in F336W (Tic-Visit :proposal-id 18131 :visit-id "07" :proposal-version -1 :trans-version "20250929" :date "08-May-2026 09:02:11.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 213904 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18131 :visit-id "07" :obset-id "07" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18131 :visit-id "07" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2597 :al-overhead-at-end 84 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18131 :visit-id "07" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2599 :al-overhead-at-end 84 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18131 :visit-id "07" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2597 :al-overhead-at-end 83 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18131 :visit-id "07" :orbit-number 4 :pcs-time 380 :si-vis-utilization 2597 :al-overhead-at-end 74 :internal-dur-at-end 270 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) true 4 0 FLASH value is determined via ETC run; the ETC assumes a transient at 25.41 mag; I have verified that even at 22 mag the image will not saturate. FLASH value is determined via ETC run; the ETC assumes a transient at 25.40 mag; I have verified that even at 22 mag the image will not saturate. FLASH value is determined via ETC run; the ETC assumes a transient at 25.43 mag; I have verified that even at 20 mag the image will not saturate. When calculating the ETC, I assumed a PSF magnitude of 18.05 mag, as is given by the