0 Assigned ID: 3794 ----- Attempting Submission 1 (Tue Aug 30 05:35:57 GMT 2022) ----- I have adjusted the program to use only two visits, updated the response time to 21 days, and adjusted the timing requirements. 587303727 ----- Attempting Submission 1 (Tue Oct 04 18:50:27 GMT 2022) ----- ----- Attempting Submission 2 (Tue Oct 18 18:48:46 GMT 2022) ----- Imaging and Spectroscopy of Three Highly Magnified Images of a Supernova at z=1.5 We have detected a strongly lensed supernova (SN) in HST imaging of the RX J2129 galaxy-cluster field acquired on August 7, 2022. The SN's apparent F110W magnitude of 24.70+-0.15 and a non-detection in F606W yield an 80% probability that the transient is a Type Ia SN. The foreground galaxy-cluster gravitational lens creates a set of three images of the SN's host galaxy at redshift 1.52, and we have detected the SN in the trailing, or last-arriving image. The other images are predicted to have arrived ~320 and ~1000 days previously. A target-of-opportunity program with HST has been triggered to measure the transient's light curve through late October. Here we propose three single-orbit WFC3 IR F110W/F160W visits followed by a two-orbit visit to measure the SN's light curve through late December. In a joint proposal, we request NIRSpec G140M and PRISM spectroscopy at the locations of all three images in early October, when the field becomes accessible to JWST. If the SN is a Type Ia SN, then we will be able to calibrate its luminosity and directly measure its magnification. This will provide a novel test of galaxy-cluster mass models. The spectra will enable comparision with low-redshift SNe Ia to address an important systematic that may affect SN Ia cosmology. We also propose for deep JWST NIRCam imaging to measure the flux of the previous arrival of the SN. With 5-sigma limiting depth of 29.2, imaging in F150W can be expected to detect the fading image. Its brightness will constrain the SN's age, and therefore the image's relative time delay. A strong detection and well-characterized SN Ia may enable a new, independent measurement of the Hubble constant. We will acquire F110W and F160W imaging in three visits following the final scheduled visit from GO-16264 (PI: Pierel). Each visit will be split between F110W and F160 WFC3 IR imaging acquired with a dither pattern. The F160W imaging is scheduled for the beginning and end of the visit to minimize Zodaical light contamination of the F110W. The field has visibility through December 23rd, 2022. Visit 18 of GO-16264 is scheduled for Oct 31, 2022 - Nov 10, 2022, and there are two remaining visits scheduled to follow by 10-14 days. Therefore, GO-16264 should be able to acquire observations the week of Nov 11 - 21 and then Nov 22 - Dec 1. Therefore, we hope to schedule visit 1, 2, and 3 for Dec 1 - Dec 8, Dec 9-Dec 17, and then Dec 18-23. Dr. Patrick Kelly has extensive experience with Hubble Space Telescope (HST) imaging programs, and discovered the multiply imaged SN Refsdal at z=1.49 in the MACS J1149 field. Dr. Kelly found the first example of a highly magnified star. Dr. Koekemoer contributes expertise in JWST and HST observing and analysis. Dr. Wenlei Chen discovered the "Warhol" highly magnified blue supergiant at z=0.94. Dr. Treu leads the JWST GLASS ERS program. Dr. Jose Diego has performed the first ray tracing simulations of the effect of compact objects in a foreground galaxy lens on the light curve of a highly magnified star. Dr. Adi Zitrin is an expert in galaxy-cluster modeling and high-redshift galaxy populations. Dr. Alex Filippenko has extensive expertise with HST observations and the study of transients. Dr. Tommaso Treu has led many HST programs, including campaigns to study galaxy clusters, and has expertise in gravitational lensing as well as lensed galaxy populations. Dr. Lou Strolger is an expert in supernova rates. He will consult on the analysis, and assist in the interpretation, and contribute to the dissemination of results. Large Scale Structure of the Universe Stellar Physics and Stellar Types 0 false SUPPORTED EXT-STAR SUPERNOVA J2000 WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W Timing link suitability includes constraints ([02 After 01 by 10.0 to 16.0 days]) The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. 3 short WFC3-IR F110W and 3 short WFC3-IR F160W exposures of new source in RX-J2129 field. 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CASM was run in Phase II mode. /private/var/folders/qs/5dtz62fx76s2bdcs0dplxycw0000gp/T/OPVisit12931043917746272756.xml 3 short WFC3-IR F110W and 3 short WFC3-IR F160W exposures of new source in RX-J2129 field. 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