{
  "bibcode": "2012GCN.14117....1V",
  "body": "K. Varela (MPE Garching), V. Sudilovsky (MPE Garching), S. Klose (TLS\nTautenburg), and J. Greiner (MPE\nGarching) report on behalf of the GROND team:\n\nWe observed the field of GRB 121229A (Swift trigger 544347; Sonbas et al.,\nGCN 14115) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,\nPASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla\nObservatory (Chile).\n\nObservations started on December 29, 2012, at 05:09 UT, 540 s after the\nGRB trigger. They were performed at an average seeing of 1.0\" and at an\naverage airmass of 1.8.\n\nWe find a point source at the border of the XRT error\ncircle at a position\n\nRA (J2000.0) = 12:40:24.29\nDEC (J2000.0) = -50:35:39.48\n\nwith an uncertainty of 0.5\" in each coordinate.\n\nBased on a total exposure time of 1500 s in g'r'i'z' and 1200 s in JHK,\nat a midtime of 3840s after the burst, we estimate preliminary\nAB magnitudes of\n\ng' = 22.2 +/- 0.2,\nr' = 21.5 +/- 0.1,\ni' = 21.3 +/- 0.1,\nz' = 21.1 +/- 0.1,\nJ  = 20.9 +/- 0.1,\nH  = 20.2 +/- 0.1, and\nK  > 19.7.\n\nThis source's spectral energy distribution is best fit with a power-law of\nslope beta = 0.8 +/- 0.2.\nWe suggest that this source is the afterglow of GRB 121229A.\n\nGiven magnitudes are calibrated against GROND zeropoints in g'r'i'z' and\n2MASS\nfield stars in JHK, and are not corrected for the Galactic foreground\nextinction\ncorresponding to a reddening of E(B-V)= 0.16 mag in the direction of the\nburst (Schlegel et al. 1998).",
  "circularId": 14117,
  "createdOn": 1356764360000,
  "email": "vsudilov@mpe.mpg.de",
  "subject": "GRB 121229A: GROND detection of the afterglow",
  "submitter": "Vladimir Sudilovsky at MPE  <vsudilov@mpe.mpg.de>",
  "eventId": "GRB 121229A"
}