{
  "bibcode": "2009GCN..9190....1B",
  "body": "I. Bikmaev, R.Zhuchkov, N. Sakhibullin (KSU/AST),\nI. Khamitov, Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.),\nR. Burenin, M. Pavlinsky, R. Sunyaev (IKI) \n\nreport:\n\nThe optical afterglow of GRB 090418A (Chornock et al., GCN 9148, Mangano et\nal., GCN 9149) was observed with Russian-Turkish 1.5-m telescope (RTT150,\nBakirlitepe, TUBITAK National Observatory, Turkey) under moderate\ntransparences. We obtained series of 600s exposures in BVRc filters,\ncentered at April 18, 23:40 UT, i.e. 0.52 days after the burst.\n\nThe afterglow is clearly seen at combined R image, and marginally detected\nat combined B,V frames.\n\nUsing the same calibration star USNO-B1.0 1234-0288651 as Pavlenko et\nal. (GCN 9179), we estimate the following magnitudes of OT:\n\nFilter, Exposure, mag.,     err.\n         (s)\nB       3x600     23.5    limit\nV       3x600     22.7    limit\nR       4x600     22.1    +/- 0.1\n\nWe made also series of 3x900 sec exposures in Rc filter centered on April\n20, 23:00, i.e. 2.5 days after the burst. The afterglow was not detected on\nthe combined frame with a limit R=23.3 mag\n\nRTT150 finding chart (Rc) can be found at:\n\nhttp://hea.iki.rssi.ru/grb/090418a/indexeng.html",
  "circularId": 9190,
  "createdOn": 1240398431000,
  "email": "rodion@hea.iki.rssi.ru",
  "subject": "GRB 090418A: RTT150 optical observations",
  "submitter": "Rodion Burenin at IKI, Moscow  <rodion@hea.iki.rssi.ru>",
  "eventId": "GRB 090418A"
}