{
  "editedOn": 1731009168550,
  "eventId": "GRB 130831A",
  "email": "natbutler@asu.edu",
  "version": 2,
  "format": "text/plain",
  "circularId": 15242,
  "bibcode": "2013GCN.15242....1L",
  "subject": "GRB 130831A: RATIR Confirmation of NIR/Optical Afterglow Flattening",
  "body": "William H. Lee (UNAM), Alan M. Watson (UNAM), Nat Butler (ASU), Alexander\nKutyrev (GSFC), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB),\nJ. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),\nEleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),\nJosé A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM),\nCarlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)\nreport:\n\nWe again observed the field of GRB 130831A (Hagen, et al., GCN 15139) with\nthe Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on\nthe 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional\non Sierra San Pedro Mártir from 2013/09 22.11 to 2013/09 22.31 UTC (21.57\nto 21.77 days after the BAT trigger), obtaining a total of 6.40 hours\nexposure in the r and i bands and 2.60 hours exposure in the Z, Y, J, and H\nbands.\n\nFor a source within the Swift-XRT error circle (Evans et al., GCN 15147),\nin comparison with SDSS DR9 and 2MASS, we obtain the following detections\nand upper limits (3-sigma):\n\n  r     23.02 +/- 0.14\n  i     22.78 +/- 0.13\n  Z     > 22.87\n  Y     > 22.35\n  J     21.62 +/- 0.19\n  H     > 21.75\n\nThese magnitudes are in the AB system and are not corrected for Galactic\nextinction in the direction of the GRB.  The flux levels are consistent\nwith our prior upper limits measured 4 days after the GRB (Butler et al.,\nGCN 15179) and with the measurements reported by Pozanenko et al. (GCN\n15237), confirming a flattening of the afterglow light curve.\n\nWe thank the staff of the Observatorio Astronómico Nacional in San Pedro\nMártir.",
  "submitter": "Nat Butler at Az State U  <natbutler@asu.edu>",
  "createdOn": 1379862322000,
  "editedBy": "Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>"
}