[vsnet-grb-info 2843] GRB060203: WHT Z-band observations
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Mon Feb 6 08:31:20 JST 2006
TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 4680
SUBJECT: GRB060203: WHT Z-band observations
DATE: 06/02/05 23:28:39 GMT
FROM: Evert Rol at U.Leicester <er45 at star.le.ac.uk>
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.
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