TITLE:   GCN CIRCULAR
NUMBER:  45717
SUBJECT: GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
DATE:    26/09/24 07:10:50 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct@iaa.es>


Y.-D. Hu (GXI), A. Sota, E. Fernandez-Garcia, A. J. Castro-Tirado, I. Perez-Garcia, M.D. Caballero-Garcia  and M. Gritsevich (IAA-CSIC), on behalf of a larger collaboration, report:

Following the detection of GRB 260924A by both Fermi (Fermi team, GCN 45712) and Swift (D'Elia et al. GCN 45713), we triggered the 1.5m telescope at Sierra Nevada Observatory (OSN) in Granada (Spain), starting on Sep 24, 04:24 UT (~3.18 h post trigger) in the BVRI filters. An uncatalogued object is detected within the XRT error circle (Evans et al. GCNC 45715) with R=15.5+-0.1 mag (calibrated with USNO B2), which we propose to be the GRB 260924A optical afterglow. Spectroscopic observations are encouraged.

We thank the staff at OSN for their excellent support.