{
  "bibcode": "2018GCN.22631....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 180410A (Gropp et al., GCN 22620) with the\nReionization and Transients Infrared Camera (RATIR; www.ratir.org) on the\n1.5m Harold Johnson Telescope at the Observatorio Astron��mico Nacional on\nSierra San Pedro M��rtir from 2018/04 11.13 to 2018/04 11.25 UTC (19.10\nto 21.87 hours after the BAT trigger), obtaining a total of 2.13 hours\nexposure in the r and i bands.\n\nFor a source within the Swift-XRT error circle, in comparison with the USNO-B1 and 2MASS catalogs, we\nobtain the following upper limits (3-sigma):\n\n r\t> 24.20\n i\t> 23.90\n\nThese magnitudes are in the AB system and are not corrected for Galactic\nextinction in the direction of the GRB.\n\nThe XRT error region is only 2.8 arcsec from a previously cataloged star with r = 18.1 and i = 17.4. Thus, our formal upper limits given above may be optimistic.\n\nWe thank the staff of the Observatorio Astron��mico Nacional in San Pedro \nM��rtir.",
  "circularId": 22631,
  "createdOn": 1523462618000,
  "email": "alan@astro.unam.mx",
  "subject": "GRB 180410A: RATIR Optical Observations",
  "submitter": "Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>",
  "eventId": "GRB 180410A"
}