{
  "bibcode": "2008GCN..8257....1C",
  "body": "C. Clemens (MPE), A. Rossi (Tautenburg Obs.), J. Greiner and S. McBreen (both \nMPE) report on behalf of the GROND team:\n\nGROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI \ntelescope at La Silla Observatory (Chile) observed the field of GRB 080916C, \nwhich triggered Fermi GBM (Goldstein et al., GCN #8245) and for which \nsignificant correlated emission was detected by the Fermi LAT (Tajima et al., \nGCN #8246). The field was followed up by Swift XRT (Kennea et al., GCN \n#8253).\n\nObservations started at 07:57 UT on September 17th, 2008, 31.7 hr after the \nGBM trigger. They were performed at an average seeing of 1.5\" and at an \naverage airmass of 1.7 as well as under bright moon.\n\nWe found a faint source at the edge of the astrometrically corrected 2.1'' \nSwift-XRT error circle reported by Evans et al. (GCN #8255) at\n\nRA (J2000.0) = 07h 59m 23.32s\nDEC (J2000.0) = -56d 38' 18.0''\n\nwith an uncertainty of 0.5\".\n\nBased on the first 50 min of effective exposures, we estimate a preliminary \nmagnitude of\n\nz' ~ 21.74 mag +/- 0.17.\n\nGiven magnitude is calibrated against USNO-B1 field stars.\n\nNo statement about variability can be made at this point. Further observations \nare planned.\n\nPlease note, that no correction for the Galactic foreground reddening of \nE(B-V) = 0.32 mag (Schlegel et al., 1998) has been applied.",
  "circularId": 8257,
  "createdOn": 1221648942000,
  "email": "cclemens@mpe.mpg.de",
  "subject": "GRB 080916C: GROND Detection of the Optical Afterglow Candidate",
  "submitter": "Christian Clemens at MPE  <cclemens@mpe.mpg.de>",
  "eventId": "GRB 080916C"
}