{
  "bibcode": "2006GCN..4860....1S",
  "body": "B. E. Schaefer (Louisiana State), F. Yuan (U Mich), S.A. Yost (U Mich), R. \nQuimby (U Texas), report on behalf of the ROTSE collaboration:\n\nROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB\n060312 (Swift trigger 201391; D. Grupe et al. 2005, GCN 4859), producing\nimages beginning 6.0 s after the GCN notice time. An automated response\ntook the first image at 01:36:33.0 UT, 20.3 s after the burst trigger. We\ntook 10 5-sec, 10 20-sec and 74 60-sec eposures; with ongoing imaging. The\nfirst 25 images were taken with moderate twilight and thin clouds, but\nafter this there appears to be no problem with the sky conditions. 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. In particular, we see no source at the location \nof the XRT fading transient (Grupe et al. 2005). Individual images have \nlimiting magnitudes ranging from 14.4-17.5; we set the following specific \nlimits.\n\nstart UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?\n--------------------------------------------------------------------\n01:36:33.0 01:36:38.0 5 14.6 20.3 N\n01:47:39.9 01:52:22.2 282 17.1 687.2 Y\n01:57:23.3 02:02:06.5 283 18.3 1270.6 Y",
  "circularId": 4860,
  "createdOn": 1142130869000,
  "email": "schaefer@grb.phys.lsu.edu",
  "subject": "GRB 060312: ROTSE-III Optical Limits",
  "submitter": "Brad Schaefer at LSU  <schaefer@grb.phys.lsu.edu>",
  "eventId": "GRB 060312"
}