{
  "bibcode": "2009GCN.10149....1S",
  "body": "B. E. Schaefer (Louisiana State), E.S. Rykoff (UCSB), T. Guver (U \nArizona), H. Flewelling (IfA/Hawaii), S. B. Pandey (U Mich), report on \nbehalf of the ROTSE collaboration:\n\nROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, \nresponded to GRB 091109B (Swift trigger 375409; S. R. Oates et al., GCN \n10148), producing images beginning 9.4 s after the GCN notice time. An \nautomated response took the first image at 21:49:24.5 UT, 21.6 s after the \nburst, under excellent conditions. We took 10 5-sec, 10 20-sec and 10 \n60-sec exposures. These unfiltered images are calibrated relative to USNO \nA2.0 (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; the field is not crowded. Individual \nimages have limiting magnitudes ranging from 15.9-17.0; we set the \nfollowing specific limits.\n\nstart UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?\n--------------------------------------------------------------------\n21:49:24.5   21:49:29.5         5     16.0           21.6       N\n21:49:24.4   21:50:40.5        76     16.9           21.5       Y",
  "circularId": 10149,
  "createdOn": 1257805508000,
  "email": "schaefer@grb.phys.lsu.edu",
  "subject": "GRB 091109B: ROTSE-III Optical Limits",
  "submitter": "Brad Schaefer at LSU  <schaefer@grb.phys.lsu.edu>",
  "eventId": "GRB 091109B"
}