{
  "bibcode": "2008GCN..8075....1K",
  "body": "T. Kruehler, F. Schrey, J. Greiner, A. Yoldas, C. Clemens, S. McBreen \n(all MPE Garching),\nA. Kupcu Yoldas (ESO) and G. Szokoly (Eoetvoes Univ., Budapest) report on\nbehalf of the GROND team:\n\nGROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m ESO/MPI\ntelescope at La Silla Observatory (Chile), started observations of the\nfield of GRB 080804 (Racusin et al. 2008, GCN #8057) in g'r'i'z'JHK at\n23:26 UT, 16 min after the burst. We clearly detect the optical\nafterglow (Rujopakarn & Rykoff 2008, GCN #8056) in all filters at a\nposition consistent with UVOT (Racusin et al. 2008, GCN #8057) and the\nFaulkes Telescope South (Guidorzi & Steele, GCN #8064). Observations\ncontinued for 65 min and were resumed at 06:30 UT for 30 min.\n\nAssuming the USNO-B1 star at RA(J2000)=328.6627, DEC(J2000)=-53.18288\nhaving R2=18.08 mag, we measure the following r' magnitudes, not\ncorrected for the expected Galactic foreground extinction corresponding\nto a reddening of E_(B-V)=0.02 (Schlegel et al. 1998):\n\nFilter T_mid    Exposure     Brightness\n          (s)         (s)               (mag)\n-----------------------------------------\nr'      1160       67        18.09 +- 0.03\nr'      1565       67        18.37 +- 0.03\nr'      1996       115       18.66 +- 0.02\nr'      2768       115       18.96 +- 0.02\nr'      3672       375       19.25 +- 0.02\nr'      26112     375       21.02 +- 0.04\n\n\nThe reported magnitudes are a subset of the complete observation\nconsisting of 24 individual frames. The total r band light curve is well\nfitted by power law with index of 0.87 +- 0.03 between 0.32 h and 7.63 h\npost burst. This decline is consistent with the Faulkes Telescope South\ndetection (Guidorzi & Steele, GCN #8064) at 14.235 h post burst.\n\nAssuming the optical light curve continues the decline with the same \npower law index, we predict r' band magnitudes of 22.7 at 2 days and \n23.4 at 4 days post burst.\n\nThe broad band SED from g' to K can be fitted by a power law with index\n0.8 +- 0.1 (statistical) +-0.1 (systematic), where the latter is due to \nthe lack of photometric calibration.",
  "circularId": 8075,
  "createdOn": 1218009492000,
  "email": "kruehler@mpe.mpg.de",
  "subject": "GRB 080804: GROND observations",
  "submitter": "Thomas Kruehler at MPE/MPI  <kruehler@mpe.mpg.de>",
  "eventId": "GRB 080804"
}