TITLE: GCN CIRCULAR NUMBER: 44693 SUBJECT: GRB 260522A: GOTO optical upper limit DATE: 26/05/22 11:34:14 GMT FROM: d.s.oneill@bham.ac.uk D. O'Neill, G. Ramsay, A. Kumar, R. Starling, B. P. Gompertz, S. Belkin, K. Ackley, M. Dyer, J. Lyman, K. Ulaczyk, D. Steeghs, D. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. Breton, J. Casares, L. Nuttall, B. Godson, T. Killestein, M. Pursiainen, on behalf of GOTO collaboration We report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to the Fermi/GBM and LAT detected GRB 260522A (Fermi GBM team, GCN 44687; Bissaldi, E., GCN 44689). Observations covering the GBM localisation area began at 2026-05-22 03:16:58 UT (+1.03h post trigger) and continued through to 2026-05-22 04:54:51 UT (+2.66h post trigger). Observations covering the LAT position were taken at 2026-05-22 04:14:26 UT (+1.99h post trigger). Images consisted of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogs. Human vetting was carried out in real time on any candidates that passed the above checks (Lyman et al. 2026). We found no new transients that could be credibly associated with 260522A within the LAT localisation down to a 5-sigma depth of L<19.8 AB mag. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester, the University of Birmingham and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/44693. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...