TITLE:   GCN CIRCULAR
NUMBER:  44905
SUBJECT: GRB 260610B: DDOTI optical observations
DATE:    26/06/11 06:31:15 GMT
FROM:    Alan Watson at UNAM <alan@astro.unam.mx>

Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Rosa L. Becerra (UNAM), Nat Butler (ASU), Tsvetelina Dimitrova (ASU), William H. Lee (UNAM), and Margarita Pereyra (UNAM) report:

We observed the field of GRB 260610B (Fermi Team, GCN Circ. 44901) with the DDOTI wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2026-06-11 04:53 to 05:44 UTC (5.1 to 5.9 hours after the trigger) obtaining total exposure of 27 minutes.

We detect the candidate afterglow GOTO26fua/AT2026owq reported by O'Neill et al. (GCN Circ. 44903) with a preliminary AB magnitude of:

w = 18.82 +/- 0.04

Compared to the observations reported by O'Neill et al. at 0.21 hours, the candidate continues to fade and has an estimated temporal decay index of approximately −0.6, in agreement with that measured by O'Neill et al. between 0.21 and 1.4 hours.

We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir.