{
  "bibcode": "2003GCN..1857....1F",
  "body": "D.W. Fox (Caltech), P.A. Price (RSAA/ANU), T. Herter (Cornell),\nP. Appleton (IPAC), and G. Cotter (Cambridge) report on behalf of a\nlarger collaboration:\n\n\"We have observed the full corrected localization region (GCN 1847)\nfor GRB030131 with the 60-inch telescope on Mt. Palomar (P60), for\nroughly 15 min each in Gunn r and i on the night of 4 Feb 2003 UT.  We\nhave also observed a portion of this region with the 200-inch Hale\ntelescope + COSMIC (P200), for 30 min in R band on the night of 1 Feb\n2003 UT (mean epoch 10:27 UT, or 26.8 hours post-burst).\n\n\"Visual comparison of the P60 images with our summed 48-inch + NEAT\n(P48) image from 31 Jan 2003 UT (mean epoch 11:16 UT, or 3.62 hours\npost-burst; c.f. GCN 1850) reveals a point-like source in the P48\nimage that is not present in the P60 images.  The unfiltered P48\nmagnitude of this source, R~21.2 by reference to four nearby USNO-A2.0\nstars, is near the limit of the P60 r image.  However, the source lies\nwithin the field of view of the P200 R-band image, and is barely\ndetected with R>~23.5 at that time.\n\n\"The coordinates of the source relative to the GSC-II are:\n\n    RA 13:28:22.29, Dec +30:40:23.7  (J2000)\n\nwith an uncertainty of less than 1\" in each coordinate.  Inspection of\nthe individual P48 images reveals that the source is present at the\nsame position in each image (mean epochs 10:43 to 11:32 UT, 31 Jan\n2003).  The brightness of the source in the various images is roughly\nconstant, to within about one magnitude, although we observe possible\nvariability of the source within this range.\n\n\"We tentatively suggest that this source is the afterglow of\nGRB030131.  We consider this identification provisional in the absence\nof further supporting observations.\"",
  "circularId": 1857,
  "createdOn": 1044429206000,
  "email": "derekfox@astro.caltech.edu",
  "subject": "GRB030131: Candidate Optical Afterglow",
  "submitter": "Derek Fox at CIT  <derekfox@astro.caltech.edu>",
  "eventId": "GRB 030131"
}