{
  "bibcode": "2016GCN.19186....1K",
  "body": "T. Kruehler (MPE Garching), D. Malesani (DARK/NBI), D. Xu (NAOC/CAS),\nJ. Bolmer (MPE Garching), J. P. U. Fynbo, D. Perley (both DARK/NBI),\nD. A. Kann (TLS Tautenburg), J. Greiner and J. F. Graham (both MPE\nGarching) report on behalf of a larger collaboration:\n\nWe re-observed the field of GRB 160228A (Swift-trigger 676595,\nMalesani et al. GCN #19107) with GROND mounted at the 2.2m MPG\ntelescope at ESO La Silla observatory. Simultaneous observations\nin seven filters (g'r'i'z'JHK) started at 01:13 UT on 2016-03-03\n(80 h after the GRB) and consisted of images with a total\nintegration time of 72 minutes in g'r'i'z' and 60 minutes in JHK.\n\nThe source reported as candidate afterglow in our earlier imaging\n(Delvaux et al. GCN #19114) has faded beyond the detection limit\nof the new data (r' > 25.1 mag in the AB system), confirming it\nas the optical afterglow of GRB 160228A.\n\nThe nearby source (angular separation of 1.7\") mentioned in\nDelvaux et al. (GCN #19114) is still clearly present and located\nat\n\nRA (J2000.0) = 07:09:15.79\nDec. (J2000.0) = +26:55:52.4\n\nwith a preliminary brightness of r' = 24.2 +/- 0.3 mag.\n\nThe chance coincidence probability of finding an unrelated object\nof this magnitude within a distance of 1.7\" is 0.04\n(following Bloom et al. 2002, AJ, 123, 1111), and we hence\nconsider this object as a host galaxy candidate of GRB 160228A.\nWhile the chance coincidence probability is quite low, we note\nthat the angular separation would be unusually large for long GRBs.\n\nA spectrum of the possible host was taken on 2016-03-12 with the VLT\nequipped with the X-shooter spectrograph. The spectrum covers\nthe wavelength range 3000-20000 AA and has an exposure time of\n4x1200 s.  In the red part of the spectrum, we detect two emission\nlines which we interpret as [O III] (5007) and Halpha at a common\nredshift z = 1.64.\n\nWe acknowledge excellent support from the observing staff at\nLa Silla and Paranal, in particular Giovanni Carraro,\nBoris Haeussler, Jose Velasquez, and Willem-Jan de Wit.",
  "circularId": 19186,
  "createdOn": 1457977603000,
  "email": "kruehler@mpe.mpg.de",
  "subject": "GRB 160228A: GROND afterglow confirmation and X-shooter host candidate redshift",
  "submitter": "Thomas Kruehler at MPE Garching  <kruehler@mpe.mpg.de>",
  "eventId": "GRB 160228A"
}