{
  "bibcode": "2025GCN.42241....1W",
  "circularId": 42241,
  "submitter": "Alan Watson at UNAM <alan@astro.unam.mx>",
  "submittedHow": "web",
  "createdOn": 1760412373797,
  "subject": "GRB 251013C: DDOTI detection of the optical afterglow",
  "body": "Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Rosa L. Becerra (U Roma), 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 251013C detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 42221) and SVOM/ECLAIRS (Rakotondrainibe et al., GCN Circ. 42222) with the DDOTI wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) from 2025-10-14 02:41 to 03:08 (8.80 to 9.45 hours after the trigger) and obtained a total of 23 minutes of exposure in the w filter.\n\nWe detect the optical afterglow (Palmerio et al., GCN Circ. 42223; Perez-Garcia et al., GCN Circ. 42225; Konno et al., GCN Circ. 42226; Martin-Carrillo et al., GCN Circ. 42227; Masi et al., GCN Circ. 42228; Palmerio et al., GCN Circ. 42229; Moskvitin et al., GCN Circ. 42230; Gompertz et al., GCN Circ. 42231; Lipunov et al., GCN Circ. 42235; and Garnavich et al., GCN Circ. 42240) with a preliminary magnitude of\n\nw = 18.95 +/- 0.04\n\nOur photometry is calibrated against the USNO-B1 and Pan-STARRS PS1 DR2 catalogues and is not corrected for Galactic extinction.\n\nObservations are continuing.\n\nWe thank the staff of the Observatorio Astronómico Nacional at the Sierra de San Pedro Mártir for their excellent support.\n",
  "eventId": "GRB 251013C",
  "format": "text/plain"
}