{
  "circularId": 15274,
  "email": "natbutler@asu.edu",
  "subject": "GRB 130831A: Continued RATIR Optical and NIR Observations",
  "bibcode": "2013GCN.15274....1L",
  "body": "William H. Lee (UNAM), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), Nat\nButler (ASU), 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 observed the field of GRB 130831A (Hagen, et al., GCN 15139) with the\nReionization and Transients Infrared Camera (RATIR; www.ratir.org) on the\n1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on\nSierra San Pedro Mártir from 2013/09 30.12 to 2013/09 30.49 UTC (29.58 to\n29.94 days after the BAT trigger), obtaining a total of 6.27 hours exposure\nin the r and i bands and 2.65 hours exposure in the Z, Y, J, and H bands.\n\nFor a source within the Swift-XRT error circle (Evans et al., GCN 15147),\nin comparison with 2MASS, we obtain the following detections and upper\nlimits (3-sigma):\n\n  r     23.84 +/- 0.18\n  i     23.23 +/- 0.15\n  Z     > 23.04\n  Y     > 22.53\n  J     > 22.37\n  H     > 21.72\n\nThese magnitudes are in the AB system and are not corrected for Galactic\nextinction in the direction of the GRB.  The source has faded relative to\nour last measurement (t~21.5 days; Lee et al., GCN 15242) by about 0.8\nmagnitudes in r and J and 0.5 magnitudes in i.  Our measurements (see,\nalso, Watson et al., GCN 15179; Butler et al., GCN 15165) are consistent\nwith a bump or re-brightening in the lightcurve at t~10 days (see,\nPozanenko et al., GCN 15237), followed by continued fading.\n\nWe thank the staff of the Observatorio Astronómico Nacional in San Pedro\nMártir.",
  "editedOn": 1731008107765,
  "format": "text/plain",
  "submitter": "Nat Butler at Az State U  <natbutler@asu.edu>",
  "createdOn": 1380557833000,
  "eventId": "GRB 130831A",
  "version": 2,
  "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>"
}