{
  "bibcode": "2006GCN..5213....1S",
  "body": "B. E. Schaefer (Louisiana State) reports on behalf of the ROTSE \ncollaboration:\n\nROTSE-IIIa, located at Siding Spring Observatory, Australia, responded to \nGRB 060604A (Swift trigger 213486), producing images beginning 5.0 s after \nthe GCN notice time. An automated response took the first image at \n18:19:59.1 UT, 59.0 s after the burst, under excellent conditions. We took \n10 5-sec, 10 20-sec and 20 60-sec eposures, with more ongoing. These \nunfiltered images are calibrated relative to USNO A2.0 (R).\n\nComparison to the DSS (second epoch) reveals no new sources within the\n3-sigma error circle, for both single images and coadding into sets of 10;  \nthe field is not crowded.  The XRT position and the UVOT position (M. J.  \nPage et al. 2006, GCN 5212) has two faint stars nearby which might mask\nthe fast fading optical transient.  Individual images have limiting\nmagnitudes ranging from 15.2-16.9; we set the following specific limits.\n\nstart UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?\n--------------------------------------------------------------------\n18:19:59.1   18:20:19.1        20     15.8           59.0       N\n18:29:37.6   18:41:55.8       738     17.9          637.5       Y",
  "circularId": 5213,
  "createdOn": 1149448003000,
  "email": "schaefer@grb.phys.lsu.edu",
  "subject": "GRB 060604A: ROTSE-III Optical Limits",
  "submitter": "Brad Schaefer at LSU  <schaefer@grb.phys.lsu.edu>",
  "eventId": "GRB 060604A"
}