{
  "bibcode": "2016GCN.19116....1K",
  "body": "V.Krushinski, I.Zalozhnich, A. Popov\nUral State University, Kourovka\n\nE. Gorbovskoy, V. Lipunov, N.Tyurina, V.Kornilov, P.Balanutsa, \nA.Kuznetsov, D.Kuvshinov\nLomonosov Moscow State University,\nSternberg Astronomical Institute, Moscow State University\n\nA.Gabovich, V.Yurkov, Yu.Sergienko, D.Varda\nBlagoveschensk Educational State University, Blagoveschensk\n\nK.Ivanov, N.M.Budnev, O.Gres, V.A.Poleshchuk\nIrkutsk State University\n\nA. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov\nKislovodsk Solar Station of the Pulkovo Observatory\n\nR. Rebolo, M. Serra-Ricart, N. Lodieu, G. Israelian\nThe Instituto de Astrofisica de Canarias\n\n\nFive telescopes of  MASTER Net of   robotic telescope   participated in \nthe observation of the GRB 160227A. Two telescopes  detected \nprompt  optical emission. We discovery very strong OT variations with time \n~100 sec correlated with gamma ray flux (Sakamoto et al., 19106).\n\nMASTER-Ural  robotic telescope (MASTER-Net: http://observ.pereplet.ru) \nlocated in Ural was pointed to the  GRB160227A 30 sec after notice time \nand 115 sec after trigger time at 2016-02-27 19:34:03 UT. On our first \n(20s exposure)  set we  found 1 optical transient within SWIFT error-box \n(Siegel et al GCN 19098; Gorbovskoy et al GCN 19099) at a position:\nRA   12h 59m 14.13s\nDec +78d 40m 44.2s\nWith magnitude automatical magnitude ~ 17.3\nWe definetly see OT  at a number of single and coadd images. OT was \nobserved during ~ 1 hours. We see OT decay from 17.0 to 19.1 mag in the \ntime interval from 115 to 2647 sec atger the trigger.\nThe 5-sigma upper limit has been about 17.5 mag on first single image and \nup to 19.5 mag at on coadd images in later time.\n\nMASTER-Kislovodsk  robotic telescope (MASTER-Net: \nhttp://observ.pereplet.ru) \nlocated in Kislovodsk was pointed to the  GRB160227A  (Siegel et al GCN \n19098) 52 sec after notice time and 137 sec after trigger time at \n2016-02-27 19:34:25 UT. On our first (30s exposure)  set we  marginaly see \noptical transient (Siegel et al GCN 19098, Gorbovskoy et al GCN 19099) \nwithin SWIFT error-box.  OT also definetly seen at a number of coadd \nimages. OT was observed for about 4 hours. We see OT decay from 18.1 to ~ \n20.5 mag in the time interval from 152 to 12900 sec atger the trigger.\nThe 5-sigma upper limit has been about 17.5 mag on first single image and \nup to 21.0 mag at on coadd images in later time.\n\n\nMASTER-IAC  robotic telescope (MASTER-Net: http://observ.pereplet.ru) \nlocated in IAC was pointed to the  GRB160227A 49 sec after notice time and \n137 sec after trigger time at 2016-02-27 19:34:25 UT. On our first (30s \nexposure)  set we haven`t found optical transient  within SWIFT error-box. \nThe observations started on evening sky (Sun altitude ~ -6 deg). \nTherefore, the first exposure upper limit is very low.  We definetly see \nOT  at a number of coadd images, starting ~ 1 hour after the trigger. OT \nwas observed for about 2 hours. We see OT decay from 19.0 to 20.0 mag in \nthe time interval from 3400 to 9200 sec atger the trigger.\nThe 5-sigma upper limit has been about 14.5 mag (due to bright evening sky \n) on first single image and up to 21.0 mag at on coadd images in later \ntime.\n\n\nMASTER-Tunka  robotic telescope (MASTER-Net: http://observ.pereplet.ru) \nlocated in Astrophysical Center Tunka  was pointed to the  GRB160227A 17 \nsec after notice time and 103 sec after trigger time at 2016-02-27 19:33:51 UT. On our first \n(20s exposure)  set we haven`t found optical transient  within SWIFT \nerror-box. The observations made on not very well weather condition and \nwas finished 10 after GRB, due to snow coming.\nThe 5-sigma upper limit has been about 15.3 mag on first single image.\n\n\nMASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) \nlocated in Blagoveschensk was pointed to the  GRB160227A  8 sec after \nnotice time and 93 sec after trigger time at 2016-02-27 19:33:41 UT. On \nour first (20s exposure)  set we haven`t found optical transient  within \nSWIFT error-box.\nThe 5-sigma upper limit has been about 16.0 mag on first single image.\n\n\nOut preliminary photometry results available at table 1\nLight curve available here: http://master.sai.msu.ru/static/grb160227.png\n\n\nTable 1.\n\nT0-Tmig Expt.   Mag          Site            Coadd\n-------|-------|------|---------------------|------\n125     20      17.0     MASTER Ural\n152     30      18.1     MASTER Kislovodsk\n174     30      18.5     MASTER Ural\n207     120     17.8     MASTER Kislovodsk     3\n231     40      17.7     MASTER Ural\n299     50      18.9     MASTER Ural\n383     70      19.6     MASTER Ural\n485     90      17.9     MASTER Ural\n607     110     18.0     MASTER Ural\n621     550     18.7     MASTER Kislovodsk     4\n757     140     18.7     MASTER Ural\n935     170     18.2     MASTER Ural\n1133    180     19.1     MASTER Ural\n1349    180     19.0     MASTER Ural\n1566    180     18.9     MASTER Ural\n1765    1080    18.9     MASTER Kislovodsk     6\n1781    180     19.1     MASTER Ural\n1998    180     19.1     MASTER Ural\n2647    900     19.1     MASTER Ural           5\n2789    360     19.7     MASTER Kislovodsk     2\n3423    540     19.0     MASTER IAC            3\n4261    900     19.2     MASTER IAC            5\n4527    900     19.4     MASTER Kislovodsk     5\n5966    1080    19.5     MASTER Kislovodsk     6\n6401    1800    20.0     MASTER IAC           10\n7771    3600    19.9     MASTER IAC           20\n9196    1800    19.8     MASTER IAC           10\n10608   1620    20.9     MASTER Kislovodsk     9\n12824   1800    20.3     MASTER Kislovodsk    10\n\n\nThe message may be cited.",
  "circularId": 19116,
  "createdOn": 1456766115000,
  "email": "lipunov@xray.sai.msu.ru",
  "subject": "GRB 160227A: MASTER prompt OT Detection and LC",
  "submitter": "Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>",
  "eventId": "GRB 160227A"
}