{
  "bibcode": "2017GCN.20640....1K",
  "body": "T. Kruehler (MPE Garching) reports:\n\nI observed the field of GRB 170208B (Swift trigger 737463; Siegel\net al. GCN 20632) simultaneously in g'r'i'z'JHK with GROND\n(Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG\ntelescope at the ESO La Silla Observatory (Chile).\n\nObservations started at 01:22 UT on 2017-02-09, 2.8 hr after the\nGRB trigger and reveal a faint optical source centered at:\n\nRA (J2000): 08:28:34.55\nDec (J2000): -09:01:38.1\n\nwhich is 2.0\" away from the center of the XRT error circle\n(Goad et al. GCN 20635, current 90% error radius of 1.6\").\n\nBased on combined images with 66 min of total exposures in g'r'i'z'\nand 60.0 min in JHK at a mid-time of 02:39 UT on 2017-02-09, this\nsource has the following preliminary magnitudes and upper limits\n(all in the AB system):\n\ng' = 24.5 +- 0.4 mag\nr' = 24.4 +- 0.3 mag\ni' = 23.4 +- 0.2 mag\nz' = 23.1 +- 0.2 mag\nJ > 21.3 mag\nH > 21.0 mag\nK > 19.0 mag\n\nGiven magnitudes are calibrated against Pan-STARRS and 2MASS field\nstars and are not corrected for the expected Galactic foreground\nextinction corresponding to a reddening of E_(B-V)=0.042 mag in the\ndirection of the burst (Schlafly & Finkbeiner 2011).\n\nThis source is marginally detected already in the archival Pan-STARRS\nimaging of the field, so it is not the GRB 170208B afterglow. It is,\nhowever, a possible host galaxy candidate (the chance coincidence\nprobability of finding a similarly bright object at 2\" from the XRT\nposition is around 6%).\n\nI acknowledge excellent help in obtaining these data from the\nsupporting astronomers on La Silla, Sam Kim and Simon Steinmassl.",
  "circularId": 20640,
  "createdOn": 1486649312000,
  "email": "kruehler@mpe.mpg.de",
  "subject": "GRB 170208B: GROND observations",
  "submitter": "Thomas Kruehler at MPE Garching  <kruehler@mpe.mpg.de>",
  "eventId": "GRB 170208B"
}