{
  "bibcode": "2009GCN..8849....1R",
  "body": "A. Rossi (Tautenburg Obs.) and J. Greiner (MPE Garching) report on behalf \nof 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) imaged the field of GRB 090123\n(Swift trigger 340895, Grupe et al. 2009, GCN #8842) simultaneously in\ng'r'i'z'JHK. Observation started on 2009-01-24 at 01:22 UTC, about 17 hours \nafter the burst. The total exposure time was 25 minutes, the average seeing \n1.3 at airmass 2.5.\n\nWe detect the afterglow at the position reported by SWIFT UVOT (Marshall \net al 2009, GCN #8846) in g'r'i'z', but not in JHK. We estimate the following \nobserved magnitudes and upper limits (all in AB system):\n\ng' = 22.77 +- 0.05\nr' = 22.45 +- 0.05\ni' = 21.95 +- 0.08\nz' = 22.09 +- 0.12\nJ > 21.5\nH > 21.0\nK > 20.5\n\ncalibrated against GROND zeropoints and 2MASS field stars.",
  "circularId": 8849,
  "createdOn": 1232795359000,
  "email": "jcg@mpe.mpg.de",
  "subject": "GRB 090123: GROND detection",
  "submitter": "Jochen Greiner at MPI  <jcg@mpe.mpg.de>",
  "eventId": "GRB 090123"
}