{
  "bibcode": "2013GCN.15220....1G",
  "body": "E. Gorbovskoy, V. Lipunov, D.Denisenko, V.Kornilov, A.Belinski, N.Tyurina, \nD.Kuvshinov, N.Shatskiy, P.Balanutsa, A.Kuznetsov, V.V.Chazov, \nA.Sankovich,  D.Zimnukhov\nSternberg Astronomical Institute, Moscow 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\nK.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk\nIrkutsk State University\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\nMASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru)\nlocated in Kislovodsk was pointed to the  GRB130907A 18 sec  after notice\ntime and 43 sec after GRB time at 2013-09-07  21:42:00 UT in two\npolarizations. The observations were performed at low elevation (zenith \nangle 84 deg)and under the changing transparency conditions. The OT (Page et. al. \nGCN15183) appears on the 4th image in the series and is visible on four \nconsecutive  images (20, 30, 40 and 50 sec exposures) in both tubes with \nthe signal-to-noise ratio from 3 to 6. Starting with T0+5 min, the image \nquality was further deteriorating with the OT visible only on the sum of \ntwo pairs of synchronous images.\n\nOur photometry results are presented in Table 1.\n\nTable 1.\n-------\nStart date and time     exptime   T_start-T_trig   T_mid-T_trig  P| mag.   err_P      P- mag    err_P-    P| + P-    err. (P| + P-)\n-----------------------+--------+----------------+--------------+--------+---------+----------+---------+----------+---------------\n2013-09-07 21:42:00.31    10        47               52           <10.5      ---       <10.5      ---      <11.0        ---\n2013-09-07 21:42:22.79    10        69               74           <10.5      ---       <10.5      ---      <11.0        ---\n2013-09-07 21:42:43.59    20        91               101          <11.0      ---       <11.0      ---      <11.5        ---\n2013-09-07 21:43:16.66    20        123              133           12.2      0.2        13.0      0.3       12.5        0.2\n2013-09-07 21:43:47.44    30        154              169           13.3      0.4        13.6      0.6       13.5        0.4\n2013-09-07 21:44:29.95    40        197              217           13.7      0.5        13.7      0.6       13.9        0.5\n2013-09-07 21:45:21.88    50        249              274           13.7      0.5        14.4      0.8       14.0        0.6\n2013-09-07 21:46:23.87    60+80     311              387          <13.8      ---       <13.7      ---       13.9        0.6\n\n*) All time intervals in seconds.  P| and P- is an unfiltered magnitude \nwith RA and DEC orientated polaroid correspondingly.\nThe sign '<'  before magnitude means the value is upper limit.\n\n\nThe light curve and movie available here \nhttp://master.sai.msu.ru/static/GRB/GRB130907A/grb130907A.html\n\nThe epoch of our observations completely covers Swift BAT weak, soft peak \nfrom T+210 sec to T+240 sec (Cummings et. al. GCN15202).\n\nOur first automatic and not so exact (due to difficult observing \nconditions) estimation of the  OT magnitude, given in the previous \ntelegram (Gorbovskoy et. al GCN15184),  belongs to  epoch of the 5th \nexposure with t_mid=217 sec. after the trigger. This fact isn't clear from \nthe telegram  text that could mislead some researchers.\nWe apologize for this inaccuracy.\n\nThe message may be cited.",
  "circularId": 15220,
  "createdOn": 1379011618000,
  "email": "gcncirc@observ.inetcomm.ru",
  "subject": "GRB 130907A: MASTER refined analysis",
  "submitter": "Vladimir Lipunov at Moscow State U/Krylov Obs  <gcncirc@observ.inetcomm.ru>",
  "eventId": "GRB 130907A"
}