{
  "bibcode": "2015GCN.17778....1B",
  "body": "D.Buckley, S. Potter, A.Kniazev, M.Kotze\nSouth African Astronomical Observatory\n\nE. Gorbovskoy, V. Lipunov,  N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, \nD.Kuvshinov,\nLomonosov Moscow State University, Sternberg Astronomical Institute\n\nK.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk\nIrkutsk State University\n\nA. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik\nKislovodsk Solar Station of the Pulkovo Observatory\n\nV.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov\nBlagoveschensk Educational State University, Blagoveschensk\n\nV.Krushinski, I.Zalozhnih,  A. Popov\nUral Federal University, Kourovka\n\nHugo Levato and Carlos Saffe\nInstituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)\n\nClaudio Mallamaci, Carlos Lopez and Federico Podest\nObservatorio Astronomico Felix Aguilar (OAFA)\n\n\nMASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) \nlocated in SAAO was pointed to the  GRB150428A (Page et al, GCN 17765) 28 \nsec after notice time and 90 sec after trigger time at 2015-04-28 01:32:10 \nUT in two polarizations. On our first  single and coadd images  we haven`t \nfound optical transient  within SWIFT error-box . The observations made on \na high zenith distance  ~ 80 d.\nWe obtain a followin upper limits:\n\n\n\nDate start  T_s-T_tr   T_m-T_trig     Expt.  Limit Coadd\n                       (mean_time)\n01:32:10.9    90          100          20      16.0   no\n01:32:43.2   122          132          20      16.0   no\n01:33:14.7   153          168          30      16.4   no\n01:33:14.7   153          224         120      17.0    3\n01:33:14.7   153          583         770      18.5    9\n\nAlso, we can not confirm  Danish 1.56m OT (Andersen et. al GCN 17771), \nbecause they do not see it on our images with upper limits specified \nabove.\n\n\nThe message may be cited.",
  "circularId": 17778,
  "createdOn": 1430234340000,
  "email": "lipunov@xray.sai.msu.ru",
  "subject": "GRB 150428A: MASTER-net early optical observation",
  "submitter": "Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>",
  "eventId": "GRB 150428A"
}