{
  "bibcode": "2010GCN.10629....1X",
  "body": "L. Xiao (Louisiana State), W. Rujopakarn (Steward), B. E. Schaefer\n(Louisiana State), T. Guver (U Arizona) and S. B. Pandey (U Mich), report\non behalf of the ROTSE collaboration:\n\nROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB\n100420A (Swift trigger 419932; W. H. Baumgartner et al., GCN 10628),\nproducing images beginning 8.8 s after the GCN notice time. An automated\nresponse took the first image at 05:24:07.8 UT, 79.8 s after the burst, and\nduring the gamma-ray emission. We took 10 5-sec, 10 20-sec and 10 60-sec\nexposures. These unfiltered images are calibrated relative to USNO A2.0\n(R). Imaging is on going.\n\nComparison to the DSS (second epoch) reveals no new sources within the\n3-sigma Swift/BAT error circle or the XRT error circle, for both single\nimages and coadding into sets of 10. Individual images have limiting\nmagnitudes ranging from 15.3-16.8; we set the following specific limits.\n\nstart UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?\n--------------------------------------------------------------------\n05:24:07.8 05:25:14.9 67 16.7 79.8 Y\n05:25:28.5 05:30:11.0 282 17.3 160.5 Y\n05:30:20.3 05:41:42.0 681 17.6 452.3 Y",
  "circularId": 10629,
  "createdOn": 1271743514000,
  "email": "shaship@umich.edu",
  "subject": "GRB 100420A: ROTSE-III Optical Limits",
  "submitter": "Shashi Bhushan Pandey at ROTSE  <shaship@umich.edu>",
  "eventId": "GRB 100420A"
}