{
  "bibcode": "2017GCN.20582....1K",
  "body": "T. Kruehler (MPE Garching), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI),\nand Pasi J. Hakala (FINCA) report on behalf of the Nordic GRB\ncollaboration:\n\nWe observed the field of GRB 170202A (Racusin et al. GCN 20575)\nwith the NOT equipped with ALFOSC. Photometry in the r and i-band\nfilter started at 22:46 UTC on 2017-02-02, 4.3 hr after the GRB\ntrigger.\n\nCalibrating our images against magnitudes of field stars from the\nSDSS catalog, we measure a preliminary brightness of the optical\nafterglow (Racusin et al. GCN 20575, Xin et al. GCN 20576,\nLipunov et al. GCN 20578, Guidorzi et al. GCN 20579, Klotz et al.\nGCN 20580, Mori et al. GCN 20581) of\n\nr = 20.1 +- 0.1 mag.\n\nThis magnitude is not corrected for the expected foreground\nextinction corresponding to a reddening of E_B-V = 0.02 mag\n(Schlafly & Finkbeiner 2011).",
  "circularId": 20582,
  "createdOn": 1486078260000,
  "email": "kruehler@mpe.mpg.de",
  "subject": "GRB 170202A: NOT afterglow observations",
  "submitter": "Thomas Kruehler at MPE Garching  <kruehler@mpe.mpg.de>",
  "eventId": "GRB 170202A"
}