{
  "bibcode": "2015GCN.17336....1W",
  "body": "P Wiseman, J Graham, P Schady and J Greiner (All MPE Garching) report on\nbehalf of\nthe GROND team:\n\nWe observed the field of GRB 150120B (Swift trigger 627170; D'Elia et al.,\nGCN 17314) 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 01:25 UT on 21.01.2015, ~18hrs after the GRB\ntrigger. They were performed at an average seeing of 1.1\" and at an\naverage airmass of 1.7.\n\nWe find a single point source within the 1.4\" Swift-XRT error circle (Goad\net al., GCN 17320), consistent with that\nreported by Perley et al. (GCN 17315), Guidorzi et al. (GCN 17316), at\n\nRA (J2000.0) = 02 h 37 m 09.77 s\n\nDEC (J2000.0) = +08d 04' 40.49\"\n\nwith an uncertainty of 0.3\" in each coordinate.\n\nBased on 25 min of total exposures in g'r'i'z'JHK, we estimate preliminary\nmagnitudes and 3 sigma upper limits (all in AB system) of\n\ng' > 24.2\nr' = 23.6 +/- 0.1 mag,\ni' = 22.7 +/- 0.2 mag,\nz' = 22.4 +/- 0.40 mag,\nJ = 20.2 +/- 0.3 mag,\nH = 19.9 +/- 0.5 mag, and\nK = 18.7 +/- 0.4 mag.\n\nBased on these magnitudes, the best-fit SED has a break in the g' band\nsuggesting a photometric redshift of 3.5 +/-0.5.\n\nGiven magnitudes are calibrated against GROND zeropoints as well as 2MASS\nfield stars and are not corrected for the expected Galactic foreground\nextinction corresponding to a reddening of E_(B-V)=0.17 mag in the\ndirection of the burst (Schlegel et al. 1998).",
  "circularId": 17336,
  "createdOn": 1421831674000,
  "email": "wiseman@mpe.mpg.de",
  "subject": "GRB 150120B: GROND Afterglow Detection",
  "submitter": "Philip Wiseman at MPE/Swift  <wiseman@mpe.mpg.de>",
  "eventId": "GRB 150120B"
}