{
  "bibcode": "2018GCN.22465....1W",
  "body": "Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),\nWilliam H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI),\nJ. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara\n(UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico\nRamirez-Ruiz (UCSC), Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM),\nHarvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and\nVicki Toy (UMD) report:\n\nWe observed the field of GRB 180305A (Axelsson, et al., GCN Circ. 22457)\nwith the Reionization and Transients Infrared Camera (RATIR;\nwww.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio\nAstron��mico Nacional on Sierra San Pedro M��rtir from 2018/03 7.11 to\n2018/03 7.20 UTC (41.30 to 43.46 hours after the BAT trigger), obtaining\na total of 1.64 hours exposure in the r and i bands.\n\nThe source reported by Troja et al. (GCN Circ. 22460) is still detected,\nbut has faded to:\n\n r\t= 23.15 +/- 0.21\n i\t= 22.80 +/- 0.15\n\nThese magnitudes are in the AB system, are calibrated against the\nUSNO-B1 catalog, and are not corrected for Galactic extinction in the\ndirection of the GRB.\n\nThe combination of the optical fading reported here and the X-ray fading\nreported by D���Avanzo et al. (GCN Circ. 22462) confirm that this is the\nafterglow of the GRB.\n\nWe thank the staff of the Observatorio Astron��mico Nacional in San Pedro\nM��rtir.",
  "circularId": 22465,
  "createdOn": 1520434789000,
  "email": "alan@astro.unam.mx",
  "subject": "GRB 180305A: RATIR Optical Observations",
  "submitter": "Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>",
  "eventId": "GRB 180305A"
}