TITLE: GCN GRB OBSERVATION REPORT NUMBER: 823 SUBJECT: GRB000926 - Optical observations DATE: 00/09/30 21:14:00 GMT FROM: Christian Veillet at CFHT Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit GRB000926 - Optical observations The optical counterpart of GRB000926 has been observed using the CFH12K CCD mosaic camera at the prime focus of the 3.6-m CFH Telescope. One 600s exposure with moderate seeing (image quality 0.8") has been obtained and a preliminary reduction using the reference star of Halpern et al. (GCN #806) with R=17.1 gives the following measurement for GRB000926: Sept. 30.3075 R = 22.19 +/- 0.06 Added to the R-band data points used in the analysis by Hjorth et al. (GCN #814), to the previous CFHT observation and to the last data by Fynbo et al. (GCN #820), this new point confirms the change in decay rate announced in GCN #820. The decay value is now 2.44 +/- 0.07, using data past Sept 29.2, while the decay is 1.67 +/- 0.04 with data prior to Sept 29.2. A graph of the light curve in R with the linear fits can be found at http://www.cfht.hawaii.edu/~veillet/grb.html D. Kocevski, D. Donovan and G. Luppino are acknowledged for their help in this observation. This message may be cited. -- ************************************************************ Dr. Christian Veillet, CFHT Senior Resident Astronomer Phone: (808) 885-3161 http://www.cfht.hawaii.edu/~veillet/ ************************************************************