TITLE: GCN CIRCULAR NUMBER: 43811 SUBJECT: GRB 260223A: DDOTI Optical Candidate DATE: 26/02/23 05:44:22 GMT FROM: Rosa Leticia Becerra Godínez at Instituto de Astronomía, UNAM <rbecerra@astro.unam.mx> Rosa L. Becerra (UNAM), Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report: We observe the field of GRB 260223A (Fermi Team, GCN Circ. 43808) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) on the night of 2026-02-23 UTC. DDOTI observed from 04:26 UTC to 04:36 UTC (T+14.9 minutes to T+25.3 minutes after the trigger), with a total exposure time of 8 minutes. Comparing our observations with the USNO-B1 and Pan-STARRS PS1 DR2 catalogues, we detect an uncatalogued fading source at: RA = 07:24:21.20 (111.0883 deg) DEC = -29:25:04.4 (-29.4179 deg) at a preliminary AB magnitude of: w = 18.30 +/- 0.13 at T + 14.9 minutes. From our observations, we estimate a temporal decay of approximately −0.6. We suggest that this source is the optical counterpart of GRB 260223A and encourage follow-up observations. We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/43811. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...