{
  "bibcode": "2003GCN..2499....1F",
  "body": "D.B. Fox, A.M. Soderberg and E.Berger (Caltech) report on behalf of\na larger collaboration:  \n\n\"We have observed the HETE-2/SXC localization region for GRB 031220\nthrough intermittent clouds with the Palomar 200-inch (5-m) Hale\nTelescope and Large Format Camera (LFC) from 08:30 to 10:00 UT on 20\nDec 2003.  With a subset of these data we have created two coadded r'\nimages with exposures of approximately 24-min over the full SXC region\nand with mean epochs of 08:50 UT (5:20 after the GRB) and 09:47 UT\n(6:17 after the GRB), respectively.  The limiting magnitudes of these\nimages, as referenced against the R-band (F-emulsion) photometry of\nthe GSC-2, are R~23 and R~22.5, respectively, with the later\nobservations having been more strongly extinguished by cloud cover.\n\nComparison of these images to the Digitized Sky Survey reveals no new\nobjects brighter than the DSS limit.  Moreover, PSF-matched image\nsubtraction of the two images reveals no strongly variable sources\nsignificantly brighter than our limits.  Since a t^(-1) decay would\nhave produced a 0.2 mag decline between the two epochs of exposure, we\nestimate that any afterglow of GRB 031220 had R>21 at our epoch of\nfirst observation.\n\nOur coadded r' images, and their subtraction, may be found at:\n\n    http://www.astro.caltech.edu/~derekfox/grb031220/",
  "circularId": 2499,
  "createdOn": 1072009845000,
  "email": "derekfox@astro.caltech.edu",
  "subject": "GRB031220: Palomar Observations",
  "submitter": "Derek Fox at CIT  <derekfox@astro.caltech.edu>",
  "eventId": "GRB 031220"
}