GCN Circular 41209
Subject
EP250730a: COLIBRÍ optical upper limit
Event
Date
2025-07-31T07:03:35Z (3 months ago)
From
Francesco Magnani at Aix-Marseille Université, CPPM/CNRS <francesco.magnani.work@gmail.com>
Via
Web form
Francesco Magnani (CPPM), Alan M. Watson (UNAM), Rosa L. Becerra (U Roma), Antonio de Ugarte Postigo (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Sarah Antier (OCA), Jean-Luc Atteia (IRAP), Fredd Alvarez (UNAM), Camila Angulo (UNAM), Dalya Akl (AUS), 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), Margarita Pereyra (UNAM), Benjamin Schneider (LAM), and Ny Avo Rakotondrainibe (LAM):
We imaged the field the EP250730a (Wang et al., GCN Circ. 41207) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-07-31 04:13 to 05:35 UTC (from 22.1 to 23.5 hours after the trigger, starting 23 min after the report by Wang et al., GCN Circ. 41207) and obtained 64 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 within the EP/WXT uncertainty region (Wang et al., GCN Circ. 41207) to a 5-sigma upper limit of:
i > 23.1
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.