{
  "format": "text/plain",
  "version": 2,
  "subject": "GRB 130831A: Continued RATIR Optical and NIR Observations",
  "editedOn": 1731005395609,
  "email": "alan@astro.unam.mx",
  "eventId": "GRB 130831A",
  "submitter": "Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>",
  "body": "William H. Lee (UNAM), Nat Butler (ASU), Alan M. Watson (UNAM), \nAlexander Kutyrev (GSFC), Michael G. Richer (UNAM), Chris Klein (UCB),\nOri Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino\nCucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico\nRamirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM),\nJesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC),\nand Harvey Moseley (GSFC) report:\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 2013/10 9.10 to 2013/10 9.47 UTC (925.41\nto 934.19 hours after the BAT trigger), obtaining a total of 6.08 hours\nexposure in the r and i bands and 2.61 hours exposure in the Z,\nY, J, and H bands.\n\nFor a source within the Swift-XRT error circle, in comparison with 2MASS, we\nobtain the following upper limits (3-sigma):\n\n  r > 24.14\n  i > 23.63\n  Z > 22.94\n  Y > 22.45\n  J > 22.23\n  H > 21.74\n\nThese magnitudes are in the AB system and are not corrected for Galactic\nextinction in the direction of the GRB.\n\nAs compared with our previous RATIR observations (Lee et al., GCN 15274) we \nconfirm the fading in r and i by at least 0.3 and 0.4 and magnitudes, respectively. \nThe upper limits in Z, Y, J, and H are also consistent with fading. \n\nOverall our measurements (Butler et al. GCN 15165, Watson et al. GCN 15179, \nLee et al., GCN 15242, 15274) are consistent with the re-brightening due to \na SN, as reported by Pozanenko et al. (GCN 15237) and spectroscopically by \nKlose et al. (GCN 15320), and fading.\n\nWe thank the staff of the Observatorio Astronómico Nacional in San Pedro \nMártir.",
  "createdOn": 1381353720000,
  "bibcode": "2013GCN.15321....1L",
  "editedBy": "Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>",
  "circularId": 15321
}