TITLE: GCN CIRCULAR NUMBER: 43092 SUBJECT: EP251214a: COLIBRÍ optical upper limit DATE: 25/12/14 11:44:06 GMT FROM: Stephane Basa at UAR Pytheas/OHP, LAM <stephane.basa@lam.fr> Stéphane Basa (UAR Pytheas), Leonardo García García (UNAM), Noémie Globus (UNAM), Benjamin Schneider (LAM), Jean-Grégoire Ducoin (CPPM), William H. Lee (UNAM), Alan M. Watson (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), Francis Fortin (IRAP), Ramandeep Gill (UNAM), Enrique Moreno Méndez (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Nikos Mandarakas (LAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Antonio de Ugarte Postigo (LAM). We imaged the field of EP251214a (Y.-H. I. Yin et al., GCN Circ. 43087) potentially associated with GRB 251214A reported by the Fermi GBM Team (GCN Circ. 43085), using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2025-12-14 at 09:12:10.65 to 09:56:13.15 UTC (from 6.75 to 7.49 hr after the trigger) and obtained 32 minutes of simultaneous exposure in the r and z filters. The data were reduced, coadded and analyzed with the COLIBRÍ pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and was not corrected for Galactic extinction. In the stacked image, we do not detect any new source at the WXT uncertainty region (Y.-H. I. Yin et al., GCN Circ. 43087) down to the following 5-sigma limit: r > 23.1 z > 21.6 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/43092. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...