{
  "bibcode": "2014GCN.17212....1S",
  "body": "GRB 141221A: GROND Detection of the Optical/NIR Afterglow\n\nT. Schweyer, P. Wiseman, P. Schady and J. Greiner (all MPE Garching),\nreport on behalf of the GROND team:\n\nWe observed the field of GRB 141221A (Swift trigger 622006; Sonbas et al.,\nGCN #17206) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,\nPASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla\nObservatory (Chile).\n\nObservations started at 08:09:33 UT on 21/12/2014, 142 seconds after the\nGRB trigger, and continued in all bands for ~18 minutes of exposures until\nthe beginning of twilight, and in NIR for another 4 minute exposure. They\nwere performed at an average seeing of 1.7\" and at an average airmass of\n2.1.\n\nWe find a single point source, consistent with the enhanced SWIFT-XRT\nposition of Beardmore et al. (GCN #17211) and that reported by e.g. Covino\n(GCN 17208), Trotter et al. (GCN #17210),  at:\n\nRA (J2000.0) = 13h 13m 08.80s\n\nDEC (J2000.0) = + 08d 12' 18.9\"\n\nwith an uncertainty of 0.2\" in both co-ordinates.\n\nThere were problems with telescope pointing throughout the observations,\nBased on our first short exposures in grizJHK, we estimate preliminary\nmagnitudes (all in AB system) of\n\ng' = 17.1 +/- 0.1 mag,\nr' = 16.6 +/- 0.1 mag,\ni' = 16.4 +/- 0.1 mag,\nz' = 16.1 +/- 0.1 mag,\nJ = 15.7 +/- 0.1 mag,\nH = 15.4 +/- 0.1 mag, and\nK = 15.3 +/- 0.1 mag.\n\nThe best-fit SED has a spectral index beta = 1.0 +/- 0.1.\n\nGiven magnitudes are not corrected for the expected Galactic foreground\nextinction corresponding to a reddening of E_(B-V)=0.024 mag in the\ndirection of the burst (Schlegel et al. 1998).",
  "circularId": 17212,
  "createdOn": 1419188637000,
  "email": "wiseman@mpe.mpg.de",
  "subject": "GRB141221A: GROND Afterglow Detection",
  "submitter": "Philip Wiseman at MPE/Swift  <wiseman@mpe.mpg.de>",
  "eventId": "GRB 141221A"
}