{
  "bibcode": "2014GCN.16228....1M",
  "body": "A. S. Moskvitin, D. I. Makarov, A. F. Valeev, V. V. Sokolov (SAO-RAS,\nRussia), A. J. Castro-Tirado, J. Gorosabel (IAA-CSIC, Spain),\nE. S. Gorbovskoy, D. V. Denisenko, V. M.Lipunov (MASTER-team, Russia),\non behalf of a larger collaboration, report:\n\n\"Following the detection of GRB 140508A by Fermi (Yu et al. GCNC 16224) and\nthe IPN (Hurley et al. GCNC 16225), we have conducted BVRc imaging and\nspectroscopy of the iPTF optical candidate (Singer et al. GCNC 16226) with\nthe 6m BTA telescope in Zelenchukskaia, starting at 19:47:56 UT (i.e. 16.7\nhr after the trigger). The 20 minutes (noisy) spectrum, covering the range\n3800-7200 A, displays no clear absorption features, i.e. a conservative\nupper limit of z < 2.1 is derived.\n\nThe GRB OT magnitude was measured to have R = 18.7 +/- 0.05 during the BTA\nobservations spanning more than 1 hr. OT magnitudes calibrated against the\nUSNO-B1 star 1367-0290781 with R2 = 16.48.\n\nMASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru)\nlocated in Kislovodsk also pointed to the  GRB140508A  (Yu et. al GCNC\n16224, Hurley et. al. GCN 16224) ~17.5 h  after trigger time at 2014-05-08\n20:31:01.484 UT directly after sunset and weather conditions became\nsatisfactory. On the first (180s exposure) unfiltred image the iPTF\noptical transient preliminary photometry is given below:\n\n      T_start            T-T_trig  FILTER  Mag   Err.Mag Exptime\n 2014-05-08 20:31:01    17h 28m     C     18.7   0.3     180 s\n 2014-05-08 20:48:33    17h 45m     R     18.7   0.3     180 s\n 2014-05-08 20:48:33    17h 45m     V    <19.0   0.3     180 s upper limit\n 2014-05-08 21:20:36    18h 17m     R     18.9   0.3     540 s\n 2014-05-08 21:20:36    18h 17m     V     19.9   0.4     540 s\n\n \"C\" is unfiltred 0.8R+0.2B magnitude.\n\nThis message can be quoted.\"",
  "circularId": 16228,
  "createdOn": 1399598115000,
  "email": "sokolov@sao.ru",
  "subject": "GRB 140508A: SAO RAS and MASTER photometric and spectroscopic observations",
  "submitter": "Vladimir Sokolov at SAO RAS  <sokolov@sao.ru>",
  "eventId": "GRB 140508A"
}