0 Assigned ID: 2258 ----- Attempting Submission 1 (Fri Apr 09 21:10:44 GMT 2021) ----- HST Phase I Proposal 2258 successfully submitted. Receipt: # 2258-1 ----- Attempting Submission 2 (Fri Apr 09 21:32:08 GMT 2021) ----- HST Phase I Proposal 2258 successfully submitted. Receipt: # 2258-2 ----- Attempting Submission 3 (Fri Apr 09 23:58:08 GMT 2021) ----- This target is not used in this proposal. If the target position is not known to 0.4" (or better), an ACQ/SEARCH should precede the ACQ/IMAGE. If the target position is not known to 0.4" (or better), an ACQ/SEARCH should precede the ACQ/IMAGE. This is the submission of our requested observations following the identification of a suitable target for this TOO proposal. We have not changed the details of the acquisition procedure; please check this carefully. We are observing the source daily from the ground, please contact the PI for updates. The BOT returned an error for the STIS acquisition sequence. I was not able to identify the specific cause of this error; please contact me with any concerns. -2065051055 ----- Attempting Submission 1 (Fri Jul 23 17:54:43 GMT 2021) ----- ----- Attempting Submission 2 (Wed Jul 28 00:50:56 GMT 2021) ----- ----- Attempting Submission 3 (Sun May 21 21:08:26 GMT 2023) ----- The Generic TOO target does not need to be used. The target position is known to better than 0.4". HST Spectroscopy of a Fast-Rising Luminous Ultraviolet Transient High-cadence time-domain surveys have unveiled a population of fast-evolving, luminous extragalactic transients with SEDs that remain dominated by ultraviolet emission for long after peak and also exhibit luminous X-ray and radio counterparts. While they show some observational similarities with strongly-interacting supernovae, optical follow-up has failed to identify any recognizable supernova features and the extreme properties of these events strain theoretical models for what is possible in a supernova explosion. Ultraviolet spectroscopy has the power to reveal similarities or differences betwen this event and other supernova classes not apparent from optical observations alone, and offers a means of identifying the progenitor star via transmission spectroscopy of the dense stellar wind before the explosion sweeps it up. We propose to obtain target-of-opportunity UV spectroscopy of a new event of this type in Cycle 29 to secure the physical origins of this class while HST's unique UV spectroscopic resource is still available. Our objective is to carry out low-resolution FUV and NUV spectroscopy of a fast-luminous UV transient with COS (G140L) and STIS (G230L). Fast turnaround is helpful for many reasons - both to optimize the S/N (the target will not be bright) and to decrease the risk of acquisition failure if the target's UV flux evolution is different than expected. A turnaround of up to 1 week is acceptable, although for a sufficiently nearby event we may accept a longer delay. Using fewer guide stars may be acceptable to achieve faster turnaround. It is desirable in principle to obtain the COS and STIS observations close in time to each other but observing sooner in one band will almost always be preferred if the option is available. Rapid two-way communication with STScI will be necessary to correctly configure the observations and perform all safety checks to ensure a successful acquisition. The PI's mobile number is +44 745 6339330 and can be contacted 24 hours a day. Our group has extensive experience with ultraviolet spectroscopy and with fast optical transients. PI D. Perley, an assistant professor at LJMU, led an international collaboration to follow and has published a comprehensive paper on the early-through-late UVOIR observations of AT2018cow. He also discovered and has submitted a paper on AT2020xnd, another Cow-like event. Anna Ho, a postdoc at UC Berkeley, led the long-wavelength follow-up and published papers on the X-ray, submillimeter and radio properties of these events. She developed the tools that are used to scan for new fast transients in the ZTF data stream and which were used to discover AT2020xnd. Yuhan Yao is a graduate student at Caltech working on observational studies of fast UV/optical transients and other extreme transients. Shri Kulkarni is a professor at Caltech and is an expert in transient astronomy and PI of the Zwicky Transient Facility. Lin Yan and Ragnhild Lunnan are experts in superluminous supernovae (another class of hot, UV transient) and have published several papers on UV spectroscopy, and led previous HST ToO proposals on those events. Our team has proprietary access to ZTF, a fast-cadence wide-area optical survey that is well-suited to finding future examples of this class. We also have access to a variety of robotic follow-up resources to help rapidly confirm the fast-luminous nature of any candidate transient, including the Palomar 60-inch telescope and the Liverpool Telescope; plus target-of-opportunity programs on classical facilities such as Palomar and Keck. We are frequent users of Swift and have programs to study fast transients at other wavelengths, including the SMA and VLA. Stellar Physics and Stellar Types 6 false false true false false false false false SUPPORTED STAR SUPERNOVA NO Estimated magnitude is that in one week. The current (2023 May 21) magnitudes (AB) are ~18.0 in the UV bands, ~18.2 in u/g/r, and ~18.5 in i/z. The source is not currently fading significantly, although we expect it to begin fading soon. ZTF23AAKFYSP SN2023IUC J2000 STAR SUPERNOVA The target will be identified from ZTF or potentially another high-cadence optical survey. The trigger will be submitted at or after peak and there will be a clear upper limit on the flux of the target based on this. The source will probably be close to V=18.5, UV=17.5 mag at peak (AB). The source is expected to fade rapidly after peak, but this is difficult to project. The target is a point source and we expect it will be brighter than its host galaxy (in UV) but will confirm at the time of triggering. Fast rise (<3 days) to high luminosity (M ~ -20) without cooling COS/FUV Spectroscopic No No G140L 1280 STIS/NUV-MAMA Spectroscopic No No G230L 2376 The scheduling data was generated by CASM 31.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16714 :visit-id "01" :proposal-version -1 :trans-version "20220630" :date "21-May-2023 21:25:30.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 87168 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16714 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16714 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2748 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16714 :visit-id "01" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2749 :al-overhead-at-end 0 :internal-dur-at-end 360 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 2 0 The target is currently ~18 mag in the UV and ~18.3 mag in r-band. Over the past two nights its flux has not changed significantly in either band, although based on past similar objects fading is expected to set in soon. We are able to supply up-to-date magnitudes on request as needed. The scheduling data was generated by CASM 31.0. CASM was run in Phase II mode. If the target remains bright we may request a time constraint on the second visit to delay the observation for a few days to study time evolution. (For now, we are not requesting this.) (Tic-Visit :proposal-id 16714 :visit-id "02" :proposal-version -1 :trans-version "20220630" :date "21-May-2023 21:25:38.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 87168 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16714 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16714 :visit-id "02" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2748 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16714 :visit-id "02" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2749 :al-overhead-at-end 0 :internal-dur-at-end 360 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 2 0 The target is currently ~18 mag in the UV and ~18.3 mag in r-band. Over the past two nights its flux has not changed significantly in either band, although based on past similar objects fading is expected to set in soon. We are able to supply up-to-date magnitudes on request as needed. As the target is bright, it is not essential that this observation be executed alongside the other COS visit, and we may indeed prefer a gap of a few days or more between them. But, please schedule the observations as is most convenient for the schedulers. The scheduling data was generated by CASM 31.0. CASM was run in Phase II mode. It is preferable, but not required, to execute this close in time with the COS observations. (Tic-Visit :proposal-id 16714 :visit-id "03" :proposal-version -1 :trans-version "20220630" :date "21-May-2023 21:25:45.0" :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 591840 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16714 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16714 :visit-id "03" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2749 :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 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16714 :visit-id "03" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2750 :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 3142 :pcs-gap 0 ) true 2 0 The target is currently ~18 mag in the UV and ~18.3 mag in r-band. Over the past two nights its flux has not changed significantly in either band, although based on past similar objects fading is expected to set in soon. We are able to supply up-to-date magnitudes on request as needed.