{
  "bibcode": "2015GCN.17721....1B",
  "body": "I. Bikmaev, E. Irtuganov, N. Sakhibullin (KFU/AST),\nR. Burenin, M. Pavlinsky, R. Sunyaev (IKI),\nI. Khamitov, H. Kirbiyik (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)\n\nreport:\n\nThe field of the optical afterglow of GRB 150413A (Markwardt et al.,\nGCN 17688, Ivanov et al., GCN 17689) was observed with Russian-Turkish\n1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory,\nTurkey) using the TFOSC instrument.\n\nWe obtained series of Rc exposures in April 13/14 (50 frames x 300\nsec, UT = 20:27 - 02:30 ) and in April 14/15 (4 frames x 600 sec,\nUT = 22:43 - 00:28, in partially cloudy conditions). The optical\ntransient is clearly detected in each images.\n\nUsing USNO-B1 1618-0098185 star at RA,DEC = 12:41:09.18 +71:50:32.4\n(J2000) with R2 = 15.59 mag as a reference we estimated the\nR-magnitudes of the afterglow:\n\nT-T0, Mag. +/- Mag.err\n(days)\n0.2932 17.39 +/- 0.03\n0.5200 18.70 +/- 0.05\n1.4318 21.4  +/- 0.2\n\nRTT-150 light curve in April 13/14, 2015, can be found at:\n\nhttp://hea.iki.rssi.ru/grb/150413a/indexeng.html\n\nThe break in the light curve at (T-T0) = 0.33 days is evident (break\nis seen also in V-band data of Bassano Bresciano Observatory, Quadri\net al, GCN 17704).\n\nBefore the break at (T-T0) = 0.33 days, the power law decay index is\n=~0.9, and it is close to 3.0 after that. Note, that decay index is\nclose to 2.0 after (T-T0) = 0.7 days. Therefore, there are multiple\nbreaks in the OT light curve.",
  "circularId": 17721,
  "createdOn": 1429349775000,
  "email": "rodion@hea.iki.rssi.ru",
  "subject": "GRB 150413A: RTT150 optical observations",
  "submitter": "Rodion Burenin at IKI, Moscow  <rodion@hea.iki.rssi.ru>",
  "eventId": "GRB 150413A"
}