GCN Circular 45891
Subject
GRB 261010A: possible optical afterglow detected with the 1.5m OSN
Event
Date
2026-10-10T21:42:39Z (2 days ago)
From
Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct@iaa.es>
Via
email
F.J. Aceituno, E. J. Fernandez-Garcia, A. J. Castro-Tirado, I. Perez-Garcia, M.D. Caballero-Garcia, M. Gritsevich, S. Guziy (IAA-CSIC) and Y.-D. Hu (GXI), on behalf of a larger collaboration, report:
Following the detection of GRB 261010A by both Fermi (Fermi team, GCN 45888) and Swift/BAT (Lien et al. GCN 45889), we triggered the 1.5m telescope at Sierra Nevada Observatory (OSN) in Granada (Spain), starting on Oct 10, 19:49 UT (~32 min post trigger) in the VRI filters. On the coadded image (7x300s, I-band), an uncatalogued object is detected slightly outside the Swift/XRT error circle, on the outskirts of a galaxy visible in the DSS2 archival plate. For the transient we measure a preliminary magnitude of I = 21.0 mag, at coordinates (J2000) = 16:34:59.45 +26:34:57.5, in agreement with the NOT findings (O’Neill et al. GCN 45890). Further observations are needed to confirm its relation to GRB 261010A.
We thank the staff at OSN for their excellent support.