{
  "body": "Marion Guelfand (CPPM), Camila Angulo (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM),  Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata (UNAM), Massimiliano Lincetto (CPPM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), 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:\n\nWe observed the field of the EP-WXT Trigger 01709266307 (EP260601a) with the DDRAGO two-channel wide-field imager mounted on the COLIBRÍ telescope. We observed from 2026-06-02 08:36 UTC to 09:00 UTC (from 13.38 to 13.39 hours after the trigger) and obtained 20 minutes of simultaneous exposure in the r and  z filters, respectively.\n\nThe data were reduced and coadded with the COLIBRI pipeline and analysed with STDWeb/STDPipe (Karpov 2025). 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.\n\nWe detected the optical counterpart reported by Liu et al., GCN Circ. 44764. \nThe preliminary magnitude derived for that source is:\n\nr = 21.93 +/- 0.15 \nz = 21.07 +/- 0.12\n\nThe source is fading between the two observations.\n\nFurther observations are ongoing.\n\n\nWe 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.\n\nCOLIBRÍ 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.\n\n",
  "circularId": 44765,
  "submittedHow": "web",
  "createdOn": 1780398328981,
  "format": "text/plain",
  "submitter": "Marion G <marion.guelfand@gmail.com>",
  "subject": "EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations",
  "eventId": "EP260601a"
}