{
  "bibcode": "2008GCN..7803....1Z",
  "body": "R. Zhuchkov, I.Bikmaev, 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 counterpart (GCN7792, 7793, 7794, 7795, 7796, 7797, 7799)\nof GRB 080603B (GCN 7794, SWIFT trigger=313087) was observed with\nRussian-Turkish 1.5-m  telescope (RTT150, Bakirlitepe, TUBITAK\nNational Observatory, Turkey), starting at  03 June, 20:55 UT,\ni.e. ~1.3 hours after the burst, using Andor CCD.\n\nA series of 70 frames with 60sec exposure in the R and V bands were taken \nfor a time span ~ 4.5 hours. The afterglow is clearly detected  in all \nimages. Using RTT150 preliminary calibrated magnitudes for USNO-A2 \n1575-03195804 star R.A. = 11 46 09.53,  Dec. = +68 01 51.3,  V=14.2, \nR=13.8 mag, the brightness of the OT was estimated on each frame.\n\nV,R light curves are shown at:\n\nhttp://www.tug.tubitak.gov.tr/~irekk/grb/grb080603B/GRB080603B_lc.jpg\n\nHigher dispersion at (T-T0) > 4 hours must be due to high airmass\n( Z ~ 65-70 degrees).\n\nThe VR-light curves are well fitted with two power law decay functions\nwith a break about 3 hours after the burst.\n\nA power law decay indices were estimated in OT VR-light curves as follow:\n\nbefore the break\nalpha_R=-0.59+/-0.03\nalpha_V=-0.60+/-0.03\n\nafter the break\nalpha_R=-1.14+/-0.09\nalpha_V=-1.03+/-0.07\n\nThe alpha indices before the break are in good agreement with Klotz et al. \n(GCN7799) calculated for the time span between 1 and 4 hours after\nthe burst.\n\n-- \nThis message has been scanned for viruses and\ndangerous content by MailScanner, and is\nbelieved to be clean.",
  "circularId": 7803,
  "createdOn": 1212572810000,
  "email": "irekk@tug.tug.tubitak.gov.tr",
  "subject": "GRB080603B: RTT150 optical observations, break in light curves",
  "submitter": "Irek Khamitov at TUG  <irekk@tug.tug.tubitak.gov.tr>",
  "eventId": "GRB 080603B"
}