Cannot find file /Users/dperley/research/Proposals/HST/HST31/HST_C31_proposal__UV_Spectroscopy_of_a_Fast_Blue_Transient.pdf 0 Assigned ID: 4021 ----- Attempting Submission 1 (Mon May 22 09:30:50 GMT 2023) ----- 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. Revised submission with changes to the acquisition sequence in case of fading of the source beyond baseline estimates, and to account for the expected scheduling date of October 16 or 17. 1798603068 ----- Attempting Submission 1 (Fri Sep 08 07:41:01 GMT 2023) ----- ----- Attempting Submission 2 (Wed Oct 02 17:37:51 GMT 2024) ----- ----- Attempting Submission 3 (Fri Oct 04 15:44:56 GMT 2024) ----- ----- Attempting Submission 4 (Mon Oct 07 18:24:33 GMT 2024) ----- Coordinates are precise to <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 31 or 32 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 associate 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, an assistant professor at Cornell, 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 and many additional transients of this class since then. 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 X-RAY TRANSIENT NO This is a projection of the magnitude based on information available as of October 4th. The source is evolving, and updated/improved estimates can be provided later. ZTF24ABJJPBO J2000 UVM2 = 19.8 (AB, expected) 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 32.1.3. CASM was run in Phase II mode. /private/var/folders/mc/z1btllr51xsbm7yx2zhm3xdr0000gn/T/OPVisit6769215304448484232.xml (Tic-Visit :proposal-id 17477 :visit-id "01" :proposal-version -1 :trans-version "20240627" :date "07-Oct-2024 19:22:11.0" :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 17477 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17477 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2642 :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 3023 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17477 :visit-id "01" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2643 :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 3023 :pcs-gap 0 ) true 2 0 MirrorB acquisition strategy. The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. /private/var/folders/mc/z1btllr51xsbm7yx2zhm3xdr0000gn/T/OPVisit6763203965133029693.xml (Tic-Visit :proposal-id 17477 :visit-id "02" :proposal-version -1 :trans-version "20240627" :date "07-Oct-2024 19:13:44.0" :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 17477 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17477 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2642 :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 3023 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17477 :visit-id "02" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2643 :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 3023 :pcs-gap 0 ) true 2 0 MirrorA acquisition strategy. The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. /private/var/folders/mc/z1btllr51xsbm7yx2zhm3xdr0000gn/T/OPVisit12183169908941463993.xml (Tic-Visit :proposal-id 17477 :visit-id "03" :proposal-version -1 :trans-version "20240627" :date "07-Oct-2024 19:13:50.0" :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 522256 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17477 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17477 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2643 :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 3023 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17477 :visit-id "03" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2643 :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 3023 :pcs-gap 0 ) true 2 0 Updated to use 50CCD acquisition aperture in case the target is fainter than anticipated.