GCN Circular 45600
Tanishk Mohan (IITB), Geoffrey Mo (Caltech/Carnegie), Viraj Karambelkar (Columbia), Benjamin Schneider (LAM), Tomas Ahumada (NOIRLab), Robert Stein (UMD), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report:
We observed the field of GRB 260915A (Liang et al., GCN 45570, also see Hamburg et al., GCN 45574) in the near-infrared J band with the Palomar 1-m telescope, equipped with the 1.2-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024).
Observations began on 2026-09-15 at 04:56:16.725 UTC in the J band (3.74 hr after the SVOM/ECLAIRs trigger), consisting of 43*120 sec exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565).
We do not detect any new source in the SVOM/MXT localization (Liang et al., GCN 45570) and at EPF_J003237.9+081455 and EPF_J003224.9+081259 localization (Shi et al., GCN 45587) in our stacked image (Yin et al., GCN 45573; Wu et al., GCN 45575; Zhu et al., GCN 45577; Perez-Garcia et al., GCN 45578; Ducoin et al., GCN 45580; Li et al., GCN 45581; Brivio et al., GCN 45584; Li et al., GCN 45586; Shi et al., GCN 45588; Li et al., GCN 45589). We obtain the following 5-sigma upper limit: J = 19.9 mag (AB).
WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research.