GCN Circular 4680
E. Rol (U. of Leicester), A. Levan (U. of Hertsfordshire), K. Wiersema (U. of Amsterdam), P. Dobbie, D. Boyce (U. of Leicester), N. Tanvir (U. of Hertsfordshire) report on behalf of a larger collabration: We have observed the optical counterpart of GRB060203 (Malesani, GCN 4645) with the Auxiliary Port Imaging Camera on the William Herschel Telescope. We obtained two epochs of observations in Z-band. Our results of seeing-matched aperture photometry are tabulated below: time since burst exposure time seeing magnitude (hours) (seconds) (arcsec) 4.0 5 x 240 0.8 19.75 22.8 5 x 240 0.7 21.60 The statistical error on the magnitude is typically 0.01, while we estimate the zeropoint calibration error to be 0.3 magnitudes. We thus measure a decay for the optical counterpart of 1.85 +/- 0.01 magnitude over 18.8 hours, with an average decay index of 0.98 +/- 0.01.