{
  "bibcode": "2018GCN.22797....1T",
  "body": "N.Tyurina, V. Lipunov, E. Gorbovskoy, V.Kornilov,  A.Kuznetsov,\nI. Gorbunov, D. Vlasenko, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov\nLomonosov Moscow State University,\nSternberg Astronomical Institute, Moscow State University\n\nR. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres\nThe Instituto de Astrofisica de Canarias\n\nA. Tlatov, V.Senik, D. Dormidontov\nKislovodsk Solar Station of the Pulkovo Observatory\n\nR. Podesta, F. Podesta, C. Lopez, C.Francile\nObservatorio Astronomico Felix Aguilar (OAFA)\n\nH.Levato, C. Saffe\nInstituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)\n\nD. Buckley\nSouth African Astronomical Observatory\n\nO. Gres, N.M.Budnev , Yu.Ishmuhametova\nIrkutsk State University\n\nA. Gabovich, V. Yurkov, Yu. Sergienko\nBlagoveschensk Educational State University, Blagoveschensk\n\nMASTER-Kislovodsk  robotic telescope (MASTER-Net: http://observ.pereplet.ru \nLipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) ,\nlocated in Kislovodsk Solar Station of Pulkovo observatory,\nwas pointed to the Swift GRB180618A (LaPorte et al. GCN #22790; Sakamoto \net al., GCN #22796)\n25 sec after notice time and 41 sec after trigger time at 2018-06-18 \n00:43:53 UT.\nOn our first (10s exposure)  polarization set we haven`t found optical \ntransient  within SWIFT error-box (ra=169.933 dec=73.8478 r=0.05).\nThe 5-sigma upper limit has been about 15.2 mag\n\nThe observations made on zenit distance = 61 degrees, galaxy latitude b = \n42 degree.\nThe moon (24 % bright part) below the horizon (The altitude of the Moon is \n-31 degree ).\nObservations started at twilight and bad transparency.  The sun  altitude \nis -6.8 degree.\n\n  MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) \nlocated in IAC was pointed to the  GRB180618A 1734  sec after trigger time \nat 2018-06-18 01:12:07 UT.\nOn our first (180s exposure)  set we found  ~19 mag optical transient \nwithin SWIFT UVOT error-box (LaPorte et al. GCN #22790; Guidorzi et al., \nGCN #22792;).\n  The 5-sigma upper limit has been about 19.0 mag on single (180 s) and \n20.5 on coadd (1800 s) exposures.\n\n====================================================================\n  The observations made on zenit distance = 64 degrees, galaxy latitude b = \n42 degree. \nThe moon (24 % bright part) below the horizon (The altitude of the Moon is \n-15 degree ). \nThe sun  altitude  is -38.3 degree. \nThe object can be observed till sunrise at 2018-06-18 06:08:21 \nThe message may be cited.",
  "circularId": 22797,
  "createdOn": 1529409658000,
  "email": "lipunov@xray.sai.msu.ru",
  "subject": "GRB 180618A: MASTER OT observation (a short GRB with extended emission)",
  "submitter": "Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>",
  "eventId": "GRB 180618A"
}