{
  "bibcode": "2011GCN.12734....1C",
  "body": "S. B. Cenko, J. S. Bloom, J. M. Silverman, A. N. Morgan (UC Berkeley), D.\nA. Perley (Caltech), A. Cucchiara, J. X. Prochaska (UCSC / UCO Lick), A.\nV. Filippenko (UC Berkeley), and P. E. Nugent (LBNL / UC Berkeley) report\non behalf of a larger collaboration:\n\nWe have imaged the field of GRB111215A (Oates et al., GCN 12681) with the\nLow-Resolution Imaging Spectrometer (LRIS) mounted on the 10 m Keck I\ntelescope beginning at 5:12 UT on 2012 Dec 26 (~ 10.6 days after the Swift\nBAT trigger).  Near the position of the radio and mm counterpart (Horesh\net al., GCN 12710; Zauderer et al., GCN 12711), we detect a faint source\nwith coordinates:\n\n\tRA: 23:18:13.29      Dec: +32:29:38.8  (J2000.0)\n\nAstrometric calibration was performed with respect to several 2MASS point\nsources in the field of view, and we estimate an uncertainty of ~ 200 mas\nin each coordinate.  We measure a magnitude for this object of R ~ 25.2\n(referenced to nearby point sources from the Sloan Digital Sky Survey).\n\nUsing the sky density of objects of this brightness (Hogg et al., 1997,\nMNRAS, 288, 404), we estimate the probability of chance alignment (e.g.,\nBloom et al., 2002, AJ, 123, 1111) to be relatively small (<~ 1%).  We\ntherefore consider it likely that this object is associated with\nGRB111215A.\n\nA second, fainter source is visible ~ 1.5\" NE of the radio position.  The\nrelation of this source to GRB111215A is not clear at the moment, as the\nprobability of chance coincidence at this radius and brightness is not\nnegligible.",
  "circularId": 12734,
  "createdOn": 1324967087000,
  "email": "cenko@srl.caltech.edu",
  "subject": "GRB 111215A: Keck/LRIS Imaging",
  "submitter": "S. Bradley Cenko at Caltech  <cenko@srl.caltech.edu>",
  "eventId": "GRB 111215A"
}