{
  "bibcode": "2011GCN.12775....1N",
  "body": "A. Nicuesa Guelbenzu, S. Klose, D. A. Kann (all TLS Tautenburg), and J.\nGreiner (MPE Garching) report on behalf of the GROND team:\n\nWe observed the field of GRB 111229A (Lien et al., GCN 12774) \nsimultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, \n405) mounted at the 2.2-m MPG/ESO telescope on La Silla.\n\nObservations started in twilight, at 00:45 UT on December 30, 2.12 hr \nafter the burst. In the refined XRT error circle (Lien et al., GCN 12774), \nwe detect a new source in all bands which is significantly brighter than \nthe DSS2 limit at RA, DEC (J2000) = 05:05:08.84, -84:42:38.7. At a mean \ntime of December 30, 00:51 UT, in an 8min exposure, we measure the \nfollowing preliminary magnitudes (AB system):\n\n     g' = 20.50  +/- 0.04,\n     r' = 19.96  +/- 0.03,\n     i' = 19.74  +/- 0.03,\n     z' = 19.58  +/- 0.03,\n     J  = 19.01  +/- 0.11.\n\nWe propose this source to be the afterglow of GRB 111229A, implying a \nredshift of less than 3.5.\n\nAfter correcting for a Galactic reddening of 0.18 mag, the SED is best fit \nwith a spectral slope of 0.72 +/- 0.06.\n\nOptical data are calibrated against GROND zero points and NIR data against \n2MASS field stars. Observations are continuing.",
  "circularId": 12775,
  "createdOn": 1325210254000,
  "email": "klose@tls-tautenburg.de",
  "subject": "GRB 111229A: GROND afterglow candidate",
  "submitter": "Sylvio Klose at TLS Tautenburg  <klose@tls-tautenburg.de>",
  "eventId": "GRB 111229A"
}