{
  "bibcode": "2015GCN.17347....1M",
  "body": "E. Mazaeva (IKI), A. Volnova (IKI), E. Klunko (ISTP), I. Korobtsev \n(ISTP), M. Eselevich (ISTP), A. Pozanenko (IKI) report on behalf of \nlarger GRB follow-up collaboration:\n\nWe observed the field of GRB 150120B  (D'Elia et al., GCN 17314) with \nAZT-33IK telescope of Sayan observatory (Mondy) Jan., 20  starting on \n(UT) 11:42:02. We obtained 65 images in R-filter of 120 s exposure. In \ntwo combined images within  enhanced Swift-XRT error circle (Goad\net al., GCN 17320) we clearly  detect optical  afterglow (Perley et al. \nGCN 17315, Guidorzi et al. GCN 17316). Photometry of the afterglow is \nfollowing\n\nDate       UT start   t-T0     Filter   Exp.    OT    Err.\n                       (mid, days)       (s)\n\n2015-01-20 11:42:02   0.20149  R        30*120  21.25 0.22\n2015-01-20 12:42:04   0.24348  R        30*120  21.43 0.25\n\nPhotometry is based on nearby USNO B1.0 (R2) stars:\n\nUSNO-B1.0_id R\n0980-0031064 15.57\n0980-0031070 14.16\n0980-0031080 16.35\n0980-0031095 15.41",
  "circularId": 17347,
  "createdOn": 1422039655000,
  "email": "apozanen@iki.rssi.ru",
  "subject": "GRB 150120B: Mondy optical observations",
  "submitter": "Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>",
  "eventId": "GRB 150120B"
}