TITLE: GCN CIRCULAR NUMBER: 40749 SUBJECT: GRB 250615A: COLIBRÍ optical upper limit DATE: 25/06/16 15:32:51 GMT FROM: Francesco at Aix-Marseille Université, CPPM/CNRS francesco.magnani.work@gmail.com
Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Fredd Alvarez (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU) , Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Enrique Moreno Méndez (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM):
We imaged the field of the Swift GRB 250615A (Dichiara et al., GCN Circ. 40736) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-06-16 08:40 to 2025-06-16 10:46 UTC (from 10.3 to 12.3 hours after the trigger) and obtained 96 minutes of exposure in the i filter.
The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). 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 our stacked image, we do not detect any new source at the enhanced Swift-XRT position (Goad et al., GCN Circ. 40739) down to a 3-sigma limiting AB magnitude of:
i > 22.8
Our upper limit is consistent with the non-detection reported by Swift/UVOT (Kuin et al., GCN Circ. 40747) and DDOTI (Becerra et al., GCN Circ. 40748).
We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams.
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.
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