{
  "format": "text/plain",
  "body": "Rosa L. Becerra (U Roma), Sahil Atri (U Roma), Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report:\n\nWe observed the field of GRB 250521D detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 40516) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) on the night of 2025-05-22 UTC. \n\nDDOTI observed the field of GRB 250521D from 05:34 UTC to 09:09 UTC (from T+7.2 h to T+ 10.8 h after the trigger) and obtained a total exposure of 1.7 hours, alternating with other scientific programs.\n\nComparing our observations to the USNO-B1 and Pan-STARRS PS1 DR2 catalogues, we\ndetect no uncatalogued fading sources within the observed field down to a 10-sigma limiting AB magnitude of: \n\nw > 21.0\n\nThis value is not corrected for the Galactic extinction.\n\nWe thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir.\n",
  "submittedHow": "web",
  "createdOn": 1747909843618,
  "bibcode": "2025GCN.40524....1B",
  "eventId": "GRB 250521D",
  "subject": "GRB 250521D: DDOTI Optical Upper Limit",
  "circularId": 40524,
  "submitter": "Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra@roma2.infn.it>"
}