{
  "bibcode": "2016GCN.19960....1X",
  "body": "D. Xu (NAOC/CAS), D. Malesani (DARK/NBI and DTU Space), H. Dahle, B. \nRacine (Oslo U.), T. Pursimo (NOT), J. P. U. Fynbo (DARK/NBI), report on \nbehalf of a larger collaboration:\n\nWe observed the field of GRB 160927A (Gibson et al., GCN 19952) using \nthe 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC \ncamera. Observations started at 21:24:39 UT on 2016-09-27 (i.e., 3.33 hr \nafter the trigger) and 5x300s SDSS r-band frames were obtained.\n\nThe previously reported optical afterglow of the burst (Tkachenko et \nal., GCN 19954; D'Avanzo et al., GCN 19956; Wiseman et al., GCN 19959) \nis clearly detected in our stacked r-band image. It has m(r)=23.07 +/- \n0.10 at a median time of 3.56 hr post-burst, calibrated with nearby SDSS \nstars.\n\nCombined with the RTT150, TNG, and GROND data points reported in the \nabove GCN Circulars, we confirm the steepening of the afterglow \nlight-curve (Wiseman et al., GCN 19959). A rough estimate gives rise to \nalpha_1~0.6, a break time of ~3.1 hr post-burst, and alpha_2~1.7 (but \npoorly constrained).",
  "circularId": 19960,
  "createdOn": 1475041486000,
  "email": "dxu@nao.cas.cn",
  "subject": "GRB 160927A: NOT optical observations",
  "submitter": "Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>",
  "eventId": "GRB 160927A"
}