{
  "bibcode": "2022GCN.31505....1P",
  "body": "Margarita Pereyra (UNAM), Alan M. Watson (UNAM),  Nat Butler (ASU), Rosa L.\nBecerra (UNAM), Oc��lotl L��pez (UNAM), Diego Gonz��lez (UNAM), Alexander\nKutyrev (GSFC), William H. Lee (UNAM), Eleonora Troja (GSFC) and Tzveti\nDimitrova (ASU) report:\n\nWe observed the field of GRB 220118A (Klingler et al., GCN Circ. 31490 ;\nFermi GBM Team, GCN Circ. 31489) with the COATLI 50-cm telescope and\ninterim imager at the Observatorio Astron��mico Nacional on the Sierra de\nSan Pedro M��rtir (http://coatli.astroscu.unam.mx) from 2022-01-19 07:32 UTC\nto 13:26 UTC (13.24 to 19.1 hours after the trigger), obtaining a total of\n16215 seconds of exposure in the r filter.\n\nWe do not detect any uncataloged sources in the enhanced XRT error region\n(Goad et al., GCN Circ. 31495) to a 3-sigma limit of r = 22.9, which\nconfirms the afterglow fading reported by the GTI and Swift/UVOT teams\n(Kumar et al., GCN Circ. 31496; Belles et al., GCN Circ. 31498)\n\nOur r magnitudes are calibrated against the Pan-STARRS1 catalog, are on an\napproximate AB system (Becerra et al., 2019, ApJ, 872, 118), and are not\ncorrected for Galactic extinction in the direction of the GRB.\n\nWe thank the COATLI technical team and the staff of the Observatorio\nAstron��mico Nacional.",
  "circularId": 31505,
  "createdOn": 1642687836000,
  "email": "mpereyra@astro.unam.mx",
  "subject": "GRB 220118A: COATLI Optical Observations",
  "submitter": "Emma Margarita Pereyra Talamantes at IA-UNAM Ensenada  <mpereyra@astro.unam.mx>",
  "eventId": "GRB 220118A"
}