TITLE: GCN CIRCULAR NUMBER: 43286 SUBJECT: GRB 260101A: LCO detection of the optical counterpart DATE: 26/01/01 03:09:05 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es> I. Pérez-Fournon (IAC and ULL), F. Poidevin (IAC and ULL), D. Cano-Morales, A.E. Hernández-Díaz, I. Correa-Plasencia, E. Lekaroz-Urriza, M. Quintana-Ansaldo (all ULL), and A. López-Oramas (IAC and ULL) Following the detection of the long GRB 260101A, detected by Fermi (Fermi GBM team, GCN #43284) and Swift (Cenko et al., GCN #43285), we observed the field with one of the two Las Cumbres Observatory (LCO) 1-m telescopes, equipped with Sinistro cameras, located at the LCO node at McDonald Observatory, Texas. The observation, a single exposure of 180 sec in the SDSS r' filter, started on 2026-01-01 at 01:55:13 UT, about 58.7 minutes after the Fermi and Swift triggers. The optical counterpart detected by Swift UVOT (Cenko et al., GCN #43285), is clearly detected in our image with a magnitude of r' = 17.67 +/- 0.04, calibrated against PanSTARRS-1 DR2 stars and not corrected for Galactic extinction. This work makes use of observations from the Las Cumbres Observatory global telescope network (LCO program IAC2025B-008, SGLF and Superluminous Supernovae surveys). This work made use of the Astro-COLIBRI platform (P. Reichherzer et al. 2021, ApJS, 256, 5). View this GCN Circular online at https://gcn.nasa.gov/circulars/43286. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...