0 Assigned ID: 2596 ----- Attempting Submission 1 (Thu Sep 30 18:50:51 GMT 2021) ----- HST Phase I Proposal 2596 successfully submitted. Receipt: # 2596-1 ----- Attempting Submission 2 (Thu Sep 30 19:03:53 GMT 2021) ----- HST Phase I Proposal 2596 successfully submitted. Receipt: # 2596-2 ----- Attempting Submission 3 (Thu Sep 30 23:25:01 GMT 2021) ----- HST Phase I Proposal 2596 successfully submitted. Receipt: # 2596-3 editing postargs for IR exposures -1563623481 ----- Attempting Submission 1 (Thu Dec 16 21:11:03 GMT 2021) ----- HST Phase II Proposal 16877 successfully submitted. Receipt: # 16877-1 ----- Attempting Submission 2 (Thu Dec 23 18:52:21 GMT 2021) ----- ----- Attempting Submission 3 (Wed Jul 27 18:29:48 GMT 2022) ----- We propose HST mid-cycle imaging of the host galaxy of a fast radio burst (FRB) localized to milliarcsecond precision to constrain the origin of this enigmatic, highly active, repeating burst. Recent publications (based on HST observations) have established that FRBs occur primarily in star-forming galaxies with galactocentric offsets ranging from ~1 to 10 kpc. These data also indicate a high incidence of spiral arm structure in the near-IR band and suggest the frequent appearance of FRBs within these arms. With deep WFC3/UVIS 475X images we will observe the host of FRB 20201124A to precisely measure its spiral arm structure and to add to the quantitative assessment of the distribution of FRB progenitor locations relative to the arms. Following similar studies on other transients (e.g. supernovae), our experiment will yield new constraints on FRB progenitor channels by establishing the relationship of FRBs to recent star-formation and their progenitor lifetimes, using the high-resolution HST imaging in conjunction with VLA imaging of radio emission (presumed associated to recent star formation). The proposed observations with deep HST/WFC3 F160W will also determine the morphology, galactocentric offset, radial light distribution and local measure of the stellar mass surface density. The observations will utilize HST's high angular resolution imaging and UV sensitivity to measure the immediate galactic environment of this FRB and the nature of star formation to within a single pixel (0.1 kpc) of the burst's origin. We commit to rapid publication and release of the data to guide future research of this unique source. We will observe this host over 2 orbits; 1 orbit in F475X and 1 orbit in F160W. As this is a dusty, star-forming galaxy with a high extinction of E(B-V)=0.7315, we choose to observe using a broad NUV filter in order to achieve higher throughput. This will allow us to effectively image regions with current or recent star formation (and therefore younger stellar populations), make morphological measurements, achieve high contrast between arm and inter-arm regions, and sample the rest-frame NUV enabling a measurement of the SFR. The NIR will be sampled by the F160W filter in order to differentiate between the foreground and background host and study low surface brightness features that trace the older stellar population. In order to obtain images clean of cosmic rays and image artifacts and sub-sample the PSF for better pixel sampling, we will obtain 4 exposures in F475X in 1 orbit. We will use a custom 4 point dither pattern, 5 times larger than the default box pattern to dither over fixed pattern noise. These observations require no use of post-flash. To maximize UV throughput and minimize our pixel-based CTE correction, we place the target on chip 2 close to the readout. For the NIR observations, we wish to stay in the linear regime and minimize persistence with this bright target, and therefore will use SPAR25 with NSAMP of 15. Since this sets the exposure time per dither position, we end up with 7 dither positions of 353s in one orbit. We take dither positions from WFC3 ISR 2016-14 (pg 17) to get a good dither for the pixel phase and artificat mitigation. We multiply those values by 3 to better deal with IR blobs, and self persistence. We request that the NUV and NIR observations are obtained at the same ORIENT to aid in alignment of the NUV and NIR images, and will offset the images to obtain maximum overlap of the two filters. We request an orient from the NIR imaging, from -10 to +10. Alexandra Mannings (UCSC) is a 3rd year PhD student focusing on FRB host galaxy characterization and local environment studies. These data will form a chapter in her thesis. Professor Xavier Prochaska (UCSC) is an expert in cosmic baryons and experienced with measuring properties of galaxies hosting transient events (e.g. GRBs). Professor Wen-fai Fong (Northwestern) is an expert in HST observations of transients and their host galaxies (FRBs and Short gamma-ray bursts), and will aid with analysis and interpretation. Dr Marc Rafelski (STSCI) is an expert at planning for, reducing, and analyzing WFC3 data. He also has experience in measuring photometry and morphology of galaxies. Dr Stuart Ryder (Macquarie University) is an experienced user of 8 metre-class optical and infrared telescopes including Gemini, Keck, and the VLT for imaging, spectroscopy, and adaptive optics. Associate Professor Adam Deller (Swinburne University) is an expert in radio astrometry and has delivered accurate FRB positions based on radio data. Cherie Day is a graduate student working with Associate Professor Deller. Drs Ryan Shannon (Swinburne) and Clancy James (CIRA) are experts in observation of fast radio bursts and burst emission properties in the context of progenitor models. Prof. Nicolas Tejos (PUCV) is an expert in studies of the intergalactic medium and large-scale structure connection using HST UV spectroscopy and ground-based optical follow-up observations. As Chilean researcher, he has direct access to state-of-the-art ground based optical facilities located in Chile, providing further support to the follow-up campaigns of FRBs. Dr. Shivani Bhandari (JIVE) is an experienced user of Australia Telescope National Facility radio telescopes such as ASKAP, Parkes, and the Compact array. She uses these facilities to perform studies of fast radio bursts and their host galaxies. Professor Jason Hessels (University of Amsterdam & ASTRON) is an expert on high-time-resolution radio astronomy, focusing in particular on pulsars and FRBs; his research group (Benito Marcote, Kenzie Nimmo, Franz Kirsten) has led the effort to localise repeating FRBs at milli-arcsecond precision. Dr. Tarraneh Eftekhari is an expert in analyzing the radio continuum properties of FRBs and their host galaxies. Dr. Charles Kilpatrick is an expert in multi-wavelength observations of FRBs and analysis of HST imaging. Galaxies 6 false false false false false false false SUPPORTED GALAXY DISK J2000 J2000 WFC3/UVIS Imaging No No F475X WFC3/IR Imaging No No F160W POS-TARG DITHER 0.865 LINE 0.56 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 2 false 1658946073285 /private/var/folders/5w/t5vwb28d2xn1fgv2bgcs89gc0000gn/T/OPVisit17513331008117709312.xml The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. 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