{
  "eventId": "GRB 131031A",
  "bibcode": "2013GCN.15439....1L",
  "createdOn": 1383429694000,
  "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>",
  "subject": "GRB 131031A: RATIR Optical and NIR Observations and Upper Limits",
  "format": "text/plain",
  "circularId": 15439,
  "body": "Owen Littlejohns (ASU), Nat Butler (ASU), Alan M. Watson (UNAM),\nAlexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer\n(UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC),\nJosh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja\n(GSFC), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid\nGeorgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM),\nNeil Gehrels (GSFC), and Harvey Moseley (GSFC) report:\n\nWe again observed the field of GRB 131031A (Cummings et al., GCN 15421)\nwith the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)\non the 1.5m Harold Johnson Telescope at the Observatorio Astronómico\nNacional on Sierra San Pedro Mártir from 2013/11 2.09 to 2013/11 2.49 UTC\n(38.53 to 48.15 hours after the BAT trigger), obtaining a total of 6.23\nhours exposure in the r and i bands and 2.50 hours exposure in the Z, Y,\nJ, and H bands.\n\nThe source detected in the first epoch of RATIR observations (Cucchiara et\nal., GCN 15438) within the Swift-XRT error circle (Gompertz et al., GCN\n15424) and confirmed by Gorosabel et al. (GCN 15426) has faded. In\ncomparison with 2MASS, we obtain the following detections and upper limits\n(3-sigma):\n\n  r     22.98 +/- 0.11\n  i     > 22.36\n  Z     > 21.85\n  Y     > 21.78\n  J     > 21.62\n  H     > 21.19\n\nThese magnitudes are in the AB system and are not corrected for Galactic\nextinction in the direction of the GRB. In comparison to the first epoch\nof RATIR observations (Cucchiara et al., GCN 15438), the source has faded\nby 0.6 magnitudes in the r band. This is consistent with a power-law decay\nof\napproximately t^-0.75.\n\nWe thank the staff of the Observatorio Astronómico Nacional in San Pedro\nMártir.",
  "email": "olittlej@asu.edu",
  "submitter": "Owen Littlejohns at Az State U  <olittlej@asu.edu>",
  "editedOn": 1731008829211
}