TITLE:   GCN CIRCULAR
NUMBER:  45701
SUBJECT: GRB 260922A: J-band upper limit with WINTER
DATE:    26/09/23 10:30:25 GMT
FROM:    tanishk.mohan@iitb.ac.in

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 260922A (Page et al., GCN 45690; also see Beardmore et al., GCN 45696) 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 2026-09-23 at 02:21:59.754 UTC in the J band (16.36 hr after the BAT trigger), consisting of 15*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 the optical counterpart (Angulo et al., GCN 45699) in our stacked image.(Yin et al., GCN 45691; Shilling et al., GCN 45700)
We obtain the following 5-sigma upper limit: J = 18.8 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.