GCN Circular 36559

A. Kumar, B. P. Gompertz, S. Belkin, G. Ramsay, Y. Julakanti, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, F. Jimenez-Ibarra, D. O'Neill, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, E. Palle and D. Pollacco report on behalf of the GOTO collaboration:

The Gravitational-wave Optical Transient Observer (GOTO, Steeghs et al., 2022) performed targeted observations in response to Swift-detected GRB 240529A (Eyles-Ferris et al., GCN 36556
Not found
 
 
). Three epochs of targeted observations were performed by GOTO-North starting at 2024-05-29UT03:02:10.4 (3.67 minutes after the trigger). The first two targeted observations consisted of 4x90s exposures in the GOTO L-band (400-700 nm), whereas the third pointing was covered during the serendipitous survey pointing and had exposure times of 4x45 sec.

We detect the optical afterglow in all three epochs, with L-band magnitudes of 16.06 +/- 0.01, 17.55 +/- 0.03 and 17.30 +/- 0.04 at 4.5 minutes, 1.22 hours and 1.72 hours (mid-points) after trigger, respectively.

Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.

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 and the Instituto de Astrofisica de Canarias (IAC).