{
  "bibcode": "2006GCN..5044....1F",
  "body": "D. B. Fox (Penn State) and S. B. Cenko (Caltech) report on behalf of a\nlarger collaboration:\n\n\"The robotic Palomar 60-inch telescope (P60) has imaged the\nlocalization region of GRB060501 (Swift trigger 208050; La Parola et\nal., GCN 5040) in a series of exposures beginning 08:48 UT (33 minutes\nafter the burst).  We have compared our i-band images to the\nsecond-epoch digitized sky survey (XDSS) in a search for new sources\nconsistent with the XRT localization (La Parola et al., GCN 5042).  We\nestimate the XDSS limit in this region, by reference to USNO-B1.0\ncatalog photometry, as I~19.5 mag.  We note that due to the location\nof this field close to the Galactic plane, the background stellar\ndensity is large and the estimated Galactic extinction (E_(B-V)~0.3\nmag) is substantial.  In particular, there are three star-like objects\nin XDSS consistent with the XRT localization.\n\nWe find no new i-band sources within or near the XRT localization, to\na limit of I~19 mag in a coaddition of 4x60s images with mean epoch\n08:58 UT (43 minutes after the burs).\n\nA deeper coaddition of 5x150s images with mean epoch 09:47 UT (92\nminutes after the burst) reveals no new source within the XRT\nlocalization to I~21 mag.  However, we do identify a single new\npoint-like source with I~19.3 mag, 8.1\" from the center of the XRT\nlocalization, at coordinates:\n\n     R.A. 21:53:29.52, Dec. +43:59:49.9 (J2000)\n\n(estimated uncertainty of 0.3\" in each coordinate).  There is no\nevidence of this source in XDSS survey images.\n\nThe source is not resolved from a neighboring star in our earlier\nimages, which have poorer seeing; however, these images do constrain\nthe object to not be significantly brighter at 43 minutes post-burst\nthan at our first detection, 92 minutes post-burst.\n\nGiven the absence of evidence for variability, and the distance of the\nsource from the XRT position, we consider the association of this\nsource with GRB060501 tentative at this point.\"",
  "circularId": 5044,
  "createdOn": 1146501326000,
  "email": "dfox@astro.psu.edu",
  "subject": "GRB060501: P60 imaging and afterglow candidate",
  "submitter": "Derek Fox at PSU  <dfox@astro.psu.edu>",
  "eventId": "GRB 060501"
}