{
  "bibcode": "2006GCN..4680....1R",
  "body": "E. Rol (U. of Leicester), A. Levan (U. of Hertsfordshire), K. Wiersema\n(U. of Amsterdam), P. Dobbie, D. Boyce (U. of Leicester), N. Tanvir\n(U. of Hertsfordshire) report on behalf of a larger collabration:\n\nWe have observed the optical counterpart of GRB060203 (Malesani, GCN\n4645) with the Auxiliary Port Imaging Camera on the William Herschel\nTelescope. We obtained two epochs of observations in Z-band. Our\nresults of seeing-matched aperture photometry are tabulated below:\n\ntime since burst  exposure time    seeing    magnitude\n    (hours)          (seconds)     (arcsec)\n\n       4.0           5 x 240         0.8       19.75\n      22.8           5 x 240         0.7       21.60\n\nThe statistical error on the magnitude is typically 0.01, while we\nestimate the zeropoint calibration error to be 0.3 magnitudes.\n\nWe thus measure a decay for the optical counterpart of 1.85 +/- 0.01 \nmagnitude over 18.8 hours, with an average decay index of 0.98 +/- 0.01.",
  "circularId": 4680,
  "createdOn": 1139182119000,
  "email": "er45@star.le.ac.uk",
  "subject": "GRB060203: WHT Z-band observations",
  "submitter": "Evert Rol at U.Leicester  <er45@star.le.ac.uk>",
  "eventId": "GRB 060203"
}