{
  "version": 2,
  "format": "text/plain",
  "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>",
  "bibcode": "2015GCN.17754....1L",
  "subject": "GRB 150423A: Continued RATIR optical afterglow monitoring",
  "submitter": "Owen Littlejohns at Az State U  <olittlej@asu.edu>",
  "email": "olittlej@asu.edu",
  "eventId": "GRB 150423A",
  "editedOn": 1731008456386,
  "circularId": 17754,
  "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 150423A (Pagani, et al., GCN 17728)\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 2015/04 24.18 to 2015/04 24.48\nUTC (21.74 to 28.97 hours after the BAT trigger), obtaining a total of\n5.69 hours exposure in the r, i and z bands.\n\nFor a source within the Swift-XRT error circle (Evans, et al., GCN\n17735), in comparison with the SDSS DR9, we obtain the following upper\nlimits (3-sigma):\n\n  r     > 24.82\n  i     > 24.79\n  z     > 22.07\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 earlier\nepoch of RATIR observations (Littlejohns, et al., GCN 17736), these upper\nlimits indicate fading of at least 1 magnitude in the r and i bands. This\nimplies a continuing power-law decay temporal power-law index of t^-0.5\nor steeper, which is consistent with the comparison between the first\nepoch of RATIR observations and the earlier GROND measurements (Varela,\net al., GCN 17732). The magnitude of source 2, as reported in the GROND\nobservations, is consistent with being constant in both epochs of RATIR\ndata.\n\nWe thank the staff of the Observatorio Astronómico Nacional in San Pedro\nMártir.",
  "createdOn": 1429902103000
}