{
  "bibcode": "2004GCN..2919....1R",
  "body": "E. Rykoff (U. Michigan) reports on behalf of the ROTSE collaboration:\n\nROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, \nresponded to Swift GRB041228 (GCN #2918).  An automatic response was \ninitiated during early twilight hours.  The first usable image was taken \nat 28 Dec 18:38:44 UT, 7.8 hours after the burst.  We took 50 60-s \nexposures before the burst position dropped below our minimum observing \nelevation.  The unfiltered images were calibrated relative to USNO A2.0. \n  Individual images have limiting magnitudes ranging from 17-18 as the \nsky darkened.    Comparison to DSS (second epoch) reveals no new sources \nwithin the 3-sigma error circle to a limiting magnitude of 18.8 for \nstacks of 10 images taken 8.4 hours after the burst.",
  "circularId": 2919,
  "createdOn": 1104264203000,
  "email": "erykoff@umich.edu",
  "subject": "GRB041228: ROTSE-III Optical Observations",
  "submitter": "Eli Rykoff at U of Michigan/ROTSE  <erykoff@umich.edu>",
  "eventId": "GRB 041228"
}