0 Assigned ID: 5952 ----- Attempting Submission 1 (Mon Nov 04 15:09:15 GMT 2024) ----- HST Phase I Proposal 5952 successfully submitted. Receipt: # 5952-1 ----- Attempting Submission 2 (Mon Nov 04 19:58:17 GMT 2024) ----- HST Phase I Proposal 5952 successfully submitted. Receipt: # 5952-2 We could not add more dither points to Epoch 01, as the sub-exposures become too short for dumping the WFC3 buffer to be processed in parallel, which causes a significant loss of observing time in the orbit. We did add extra dithers in Epoch 02. We adjusted the exposure-level exposure times to match the lengths of the sub-exposures defined by auto-adjust (+- a few seconds), and used the built-in warnings to estimate the needed post-FLASH. We could not replicate the threshold FLASH required in the Exposure Time Calculator, so we used the higher needed FLASH value, which was given by the built-in tool. -370440735 ----- Attempting Submission 1 (Tue Nov 19 21:18:09 GMT 2024) ----- HST Phase II Proposal 17889 successfully submitted. Receipt: # 17889-1 ----- Attempting Submission 2 (Fri Nov 22 21:46:12 GMT 2024) ----- HST Phase II Proposal 17889 successfully submitted. Receipt: # 17889-2 ----- Attempting Submission 3 (Thu Nov 28 02:50:24 GMT 2024) ----- Tracking the Emergence of an Accretion Disk in an LFBOT In recent years, high-cadence wide-field surveys have revealed unexpected new classes of phenomena, including luminous fast blue optical transients (LFBOTs) such as AT2018cow. The progenitor of LFBOTs is unknown, but they likely involve the formation of an accretion disk that transitions from super-Eddington to ~sub-Eddington accretion rates on a timescale of ~100 days. One of the major clues was HST's detection of luminous UV emission at the position of AT2018cow 2-4 after the original transient. Unfortunately, in AT2018cow the lack of observations between 2 months post-transient and 2 years post-transient meant that the emergence of this luminous UV source was not observed. In this proposal we request HST UV observations of AT2024wpp, the first LFBOT that is both nearby enough and discovered early enough to obtain a detailed UV light curve on timescales spanning days to years. The goal of our DD request is to monitor the UV light curve of AT2024wpp from 2 months to 2 years post-outburs. Multi-frequency HST observations will teach us both about the progenitor of LFBOTs and about the accretion physics operating in these systems; observational constraints on disk physics in this phase would have broad astrophysical applications. In addition, detecting the transient with HST will enable precise astrometry for comparison to a later host-galaxy image, another important clue to the progenitor system. As per our Phase I proposal we request two non-disruptive ToO activations. The first will consist of 2 orbits, 4 filters total, and should take place in the window Dec 10-19 (but all 4 filters should be observed close together in time). The second is 4 orbits, 4 filters total, and should take place in the window June 18 - July 22 (but again, all 4 filters should be observed close together in time). As detailed below, our team has the scientific and technical expertise for carrying out a thorough multiwavelength observational campaign and analysis of AT2024wpp, including the prompt reduction, analysis, interpretation, and publication of the HST data requested here. Anna Ho (PI), an assistant professor at Cornell University, has six years of experience working on LFBOTs and characterizing their multiwavelength emission. She has been the lead author on six papers on LFBOTs. She identified AT2024wpp as an LFBOT candidate and has been one of the lead coordinators of the multiwavelength follow-up campaign. Daniel Perley (co-I), a staff member at Liverpool John Moores University, has over 15 years of experience in the studies of rare extragalactic transients, and has authored several papers on LFBOTs. He has been the PI of a longstanding HST proposal for ToO spectroscopy of an LFBOT, which was recently triggered on AT2024wpp, resulting in the first HST UV spectrum of an LFBOT. He is one of the lead coordinators of the multiwavelength follow-up campaign on AT2024wpp. Lin Yan (co-I) has extensive experience in observational galaxies at high redshift, and is also an expert in UV spectroscopy of Superluminous supernovae. She has led many HST programs, and will provide guidance on the reduction and analyses of the HST images obtained through this proposal. Genevieve Schroeder (co-I), a postdoc at Cornell University, is an expert on radio observations of energetic transients. She is leading the radio follow-up campaign of AT2024wpp, which includes observations using the VLA and ALMA. These observations will be obtained on the same timescale as our proposed HST observations and will be used to put together a comprehensive multiwavelength picture of this event. Gokul Prem Srinivasaragavan (co-I) is a Ph.D. candidate at the University of Maryland College Park and has experience following up energetic transients and characterizing their properties. He has been leading X-ray follow-up observations of AT2024wpp. Stellar Physics and Stellar Types 0 false SUPPORTED UNIDENTIFIED ACCRETION DISK EJECTA OPTICAL EMITTER RADIO EMITTER X-RAY EMITTER NO J2000 J2000 WFC3/UVIS Imaging No No F225W WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F225W WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W POS-TARG DITHER 0.145 LINE false false 2 46.84 WFC3-UVIS-DITHER-LINE 1 false POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 2 false The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. /Users/jasonsevilla/Documents/Cornell/Transients/HST/AT2024wpp/OP-cache/HST DD AT2024wpp Phase II-v01.xml (Tic-Visit :proposal-id 17889 :visit-id "01" :proposal-version -1 :trans-version "20240604" :date "27-Nov-2024 21:40:14.0" :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 2310000 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17889 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17889 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2640 :al-overhead-at-end 126 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3023 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17889 :visit-id "01" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2640 :al-overhead-at-end 121 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3023 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 32.1.3. 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