{
  "bibcode": "2005GCN..3798....1G",
  "body": "Mike Gladders, Edo Berger (Carnegie Observatories), Nidia Morrell, and\nMiguel Roth (Las Campanas Observatory) report:\n\n\"We imaged the field of GRB 050813 (GCN 3788) with the PANIC IR camera on\nthe Magellan/Baade 6.5-m telescope starting on 2005 Aug. 14.017 UT.\nObservations were obtained with the K-s and Y-Carnegie filters, under poor\nconditions (variable thick clouds, bright moonlight, and poor seeing of\n~1\").  Initial processing of these data suggest that this line of sight is\ncentered on a high-redshift galaxy cluster.  A composite Y-K color image,\nas well as a greyscale image of the stacked K frame is shown at:\n\n        http://www.ociw.edu:/~eberger/grb050813_panic.jpg\n\nThe apparent centrally concentrated population of faint galaxies with red\nand uniform colors is strongly suggestive of a galaxy cluster, and looks\nsimilar to extensive data taken with this instrument on known high-z\ngalaxy clusters from the Red-Sequence Cluster Survey (Gladders & Yee\n2005). The apparent size of the core of this distribution (~1 arcmin) and\nthe magnitude of the objects suggest this putative cluster is at high\nredshift (above z=0.5, and likely at z~1). The objects noted as B and C by\nGorosabel et al. (GCN 3796) in the XRT error circle are both red and\nlikely cluster ellipticals, and both are approximately K=19, based on an\ninitial calibration of the image to the 2MASS magnitude of the bright star\nto the immediate SE of these objects.\n\nGiven the low probability of a chance coincidence we suggest that GRB\n050813 most likely occurred in the cluster environment.  This supports\nrecent associations of short GRBs with old galaxies (050509b: Bloom et al.\nastro-ph/0505480; 050724: Berger et al. astro-ph/0508115).  The likely\nhigher redshift compared to the latter two events may also explain the\nfaintness of the X-ray afterglow (GCN 3790).\"\n\nFurther observations are planned.",
  "circularId": 3798,
  "createdOn": 1123997330000,
  "email": "eberger@ociw.edu",
  "subject": "GRB 050813: Magellan detection of a high redshift galaxy cluster",
  "submitter": "Edo Berger at Carnegie Obs  <eberger@ociw.edu>",
  "eventId": "GRB 050813"
}