{
  "bibcode": "2012GCN.13811....1K",
  "body": "F. Knust (MPE Garching), S. Klose, A. Nicuesa Guelbenzu (both TLS \nTautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND \nteam:\n\nWe observed the field of GRB 120923A (Swift trigger 534402; Yershov et \nal., GCN 13796) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. \n2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla \nObservatory (Chile).\n\nObservations started at 00:10 UT on Sep 24, 19 hrs after the GRB trigger, \nand are continuing. In a first 30 min exposure, at a mid time 00:35 UT, we \ndo not detect any source at the position of the NIR transient reported by \nLevan et al. (GCN 13802) down to (AB mags, 3 sigma)\n\ng' > 23.5,\nr' > 23.7,\ni' > 23.0,\nz' > 23.0,\nJ  > 21.0,\nH  > 20.4.\n\nThese uper limits are derived based on calibrating the images against \nGROND zeropoints and 2MASS field stars and are not corrected for the \nGalactic foreground extinction corresponding to a reddening of E_(B-V)= \n0.15 mag in the direction of the burst (Schlegel et al. 1998).",
  "circularId": 13811,
  "createdOn": 1348455694000,
  "email": "klose@tls-tautenburg.de",
  "subject": "GRB 120923A: GROND Upper limits",
  "submitter": "Sylvio Klose at TLS Tautenburg  <klose@tls-tautenburg.de>",
  "eventId": "GRB 120923A"
}