{
  "bibcode": "2007GCN..6359....1S",
  "body": "B. E. Schaefer (Louisiana State), W. Rujopakarn (U Mich), E.S. Rykoff (U \nMich), report on behalf of the ROTSE collaboration:\n\nROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,\nresponded to the short-burst GRB 070429B (Swift trigger 277582; Markwardt\net al. GCN 6358), producing images beginning 7.9 s after the GCN notice\ntime. An automated response took the first image at 03:09:30.9 UT, 26.5 s\nafter the burst, under excellent conditions. We took 10 5-sec, 10 20-sec\n20 60-sec exposures, and observations are continuing. These unfiltered\nimages are calibrated relative to USNO A2.0 (R).\n\nComparison to the DSS (second epoch) reveals no new sources within the \n3-sigma BAT error circle and within the error circle for the possible XRT \nsource, for both single images and coadding into sets of 10; the field is \nnot crowded. Individual images have limiting magnitudes ranging from \n15.5-17.5; we set the following specific limits.\n\nstart UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?\n--------------------------------------------------------------------\n03:09:30.9 03:09:35.9 5 15.5 26.5 N\n03:09:30.8 03:10:56.5 85 17.3 26.4 Y\n03:27:43.5 03:39:11.4 687 18.5 1119.1 Y",
  "circularId": 6359,
  "createdOn": 1177818995000,
  "email": "schaefer@grb.phys.lsu.edu",
  "subject": "GRB 070429B: ROTSE-III Optical Limits",
  "submitter": "Brad Schaefer at LSU  <schaefer@grb.phys.lsu.edu>",
  "eventId": "GRB 070429B"
}