GCN Circular 43827
Subject
EP 260225.148: COLIBRÍ Confirmation of flaring star
Date
2026-02-25T06:39:13Z (4 days ago)
From
Stephane Basa at UAR Pytheas/OHP, LAM <stephane.basa@lam.fr>
Via
Web form
Diego López-Cámara (UNAM), Stéphane Basa (UAR Pytheas), Alan M. Watson (UNAM), Rosa L. Becerra (UNAM), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Edilberto Aguilar-Ruiz (UNAM), Dalya Akl (NYUAD), Camila Angulo (UNAM), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata (UNAM), Francesco Magnani (CPPM), Nikos Mandarakas (LAM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report:
We automatically observed the field of EP-WXT trigger 01709258631 (Lui et al., GCN Circ. 43817) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-02-25 04:42 to 05:54 UTC (from 1.16 to 2.36 hours after the trigger) and obtained 55 minutes of simultaneous exposure in the r and z filters.
The data were reduced, coadded, calibrated, and analysed with the COLIBRÍ ASU pipeline. The photometry was calibrated using nearby stars from the Pan-STARRS-DR2 catalog, is in the AB system, and is not corrected for Galactic extinction. We used STDWeb (Karpov 2025) to perform image subtraction against Legacy Survey DR10 templates (Dey et al. 2019).
We do not detect any new source in the WXT uncertainty region down to the following 5-sigma limits:
r > 23.4
z > 22.4
Our observation supports that EP-WXT trigger 01709258631 is very probably due to a flaring star as announced by Cao et al. (GCN Circ. 4382517).
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.