{
  "bibcode": "2009GCN..9352....1O",
  "body": "F. Olivares (MPE Garching), S. Klose (Tautenburg), T. Kruehler, J. Greiner \n(both MPE Garching) report on behalf of the GROND team:\n\nGROND, mounted at the 2.2m on La Silla, observed the field of GRB 090510, \ndetected by Swift (Hoversten et al., GCN 9331), Fermi GBM (Guiriec et al., \nGCN 9336) and LAT (Ohno & Pelassa, GCN #9334), AGILE (Longo et al., GCN \n9343) and Konus-Wind (Golenetskii et al., GCN 9344), in g'r'i'z'JHK \nstarting at 6:34 UT on 10 May 2009.\n\nWe detect the afterglow reported by Marshall & Hoversten (GCN #9332) and \nOlofsson et al. (GCN #9338) in the optical bands. At a midtime of 9.0 h \nafter the burst, we measure the following AB magnitudes of the afterglow \nand upper limits in stacked images\n\ng' = 23.5 +/- 0.3\nr' = 23.0 +/- 0.1\ni' = 22.8 +/- 0.1\nz' = 22.6 +/- 0.1\nJ > 21.8\nH > 21.4\nK > 20.7\n\ncalibrated against the GROND zeropoints and 2MASS field stars. We caution \nthat the photometry might be contaminated by the nearby source mentioned by \nOlofsson et al. (GCN #9338).\n\nTogether with the magnitude reported by NOT (Olofsson et al. GCN #9338), \nthis implies a rapid early fading with an index of ~2 during this epoch, \nwhich is compatible to the X-ray afterglow at a similar time interval \n(Grupe & Hoversten, GCN #9341). A late flattening of the optical light \ncurve is then indicated by the UVOT detection (Kuin et al. #GCN 9351).",
  "circularId": 9352,
  "createdOn": 1242141597000,
  "email": "kruehler@mpe.mpg.de",
  "subject": "GRB 090510: GROND observations",
  "submitter": "Thomas Kruehler at MPE/MPI  <kruehler@mpe.mpg.de>",
  "eventId": "GRB 090510"
}