AstroNote 2022-169

We report the discovery of a supernova in the MACS2129 galaxy-cluster field in a multiply imaged galaxy at a redshift of z=1.52.  A transient was detected in WFC3 IR F110W imaging acquired as part of the SNAP GO-16729 program (PI: Kelly) on August 7, 2022 UT. Lens models show that the image we have detected is the trailing or last-arriving image. The Oguri et al. GLAFIC model finds that the SN’s magnification is ~4, the Zitrin et al. Light-Traces-Mass model yields magnification of 3, and a Zitrin et al. simply parameterized model predicts a magnification of 6. We measure a F110W magnitude of 24.75+-0.15 AB, and do not detect the source in the F606W imaging. The most recent HST visit to the field, by GO-16729, was on June 4 2022 UT, and the SN was not detected in the F110W imaging with a three-sigma upper limit of 25.7 mag AB. Non-disruptive follow up with HST GO-16264 (PI: Pierel) has been triggered to obtain follow-up near-infrared imaging of the supernova. The SN may become detectable from the ground.