{
  "bibcode": "2018GCN.22664....1T",
  "body": "Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM),\nAlexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM),\nOri Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB),\nAntonino Cucchiara (UVI), 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 re-observed the field of GRB 180418A (D'Elia, et al., GCN 22646) with\nthe Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on\nthe 1.5m Harold Johnson Telescope at the Observatorio Astron��mico Nacional\non Sierra San Pedro M��rtir from 2018/04 19.13 to 2018/04 19.41 UTC\n(20.47 to 27.09 hours after the BAT trigger), obtaining a total of\n4.17 hours exposure in the r and i bands.\n\nThe optical afterglow (Zheng & Filippenko, GCN 22647) is detected in all\nbands and significantly faded with respect to our first night of\nobservations (Troja et al., GCN 22652). In comparison with the\nSDSS DR9 catalog, we obtain the following detections:\n\n �� r = 23.63 +/- 0.22\n �� i = 23.14 +/- 0.16\n\nThese magnitudes are in the AB system and are not corrected for Galactic\nextinction in the direction of the GRB.\n\nWe thank the staff of the Observatorio Astron��mico Nacional in San Pedro\nM��rtir.",
  "circularId": 22664,
  "createdOn": 1524144919000,
  "email": "eleonora.troja@nasa.gov",
  "subject": "GRB 180418A: Continued RATIR Optical Observations",
  "submitter": "Eleonora Troja at GSFC  <eleonora.troja@nasa.gov>",
  "eventId": "GRB 180418A"
}