GCN Circular 45698
GRB 260922A: COLIBRÍ optical upper limits
From: Camila Angulo Valdez at UNAM
Issued: 2026-09-23 04:24 UTC
Type: GRB

Camila Angulo (UNAM), Marion Guelfand (CPPM), Noémie Globus (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Asuka Kuwata (UNAM), Massimiliano Lincetto (CPPM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM), Alan M. Watson (UNAM) report:

We imaged the field of the Swift GRB 260922A (Page et al., GCN Circ. 45690) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-09-23 02:46:11 to 03:44:26 UTC (from 16.76 to 17.75 hours after the trigger) and obtained 90 minutes of simultaneous exposure in the r and z filters.

The data were reduced, coadded and analyzed with the ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction.

In the stacked image, we do not detect any new source at the XRT source position (Beardmore et al., GCN Circ. 45696) down to the following 3-sigma limit:

r > 23.06,
z > 22.38.

This upper limit is consistent with the one reported by Yin et al. (GCN Circ. 45691).

We thank the staff of the Observatorio Astronómico Nacional at Sierra de San Pedro Mártir, as well as the technical and engineering teams at CEA, CPPM, IRAP, LAM, OHP, OSU Pytheas, and UNAM.

COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.

Filter: gamma-ray bursts are posted only if in the top 10% of the past year's — by fluence (total energy received per cm², from Fermi GBM, Konus-Wind, GECAM and similar circulars; now ≥ 3.9×10^-5 erg/cm²) or by the number of GCN Circulars about the burst (now ≥ 14). Thresholds are recalculated monthly.
Relayed automatically from NASA's General Coordinates Network.