TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  809
SUBJECT: GRB 000926: Preliminary R-band Lightcurve
DATE:    00/09/28 22:35:11 GMT
FROM:    Johan U. Fynbo at Inst. Phys. and Astro., Aarhus,Denmark  <jfynbo@eso.org>

GRB 000926: Preliminary R-band Lightcurve

J. Hjorth, B. L. Jensen, and H. Pedersen (U. of Copenhagen), 
J. U. P. Fynbo and P. Moller (ESO), J. Gorosabel (DSRI, Copenhagen)
report on behalf of a larger European GRB collaboration:

"Using the ALFOSC on the 2.56-m Nordic Optical Telescope we have
obtained R-band imaging of the optical afterglow of GRB 000926 
(GCN #801-#808) on 2000 September 27.8-28.9 UT. We find the 
following preliminary R-band magnitudes of the object using the 
reference star of Halpern et al. (GCN #806) :

Sept. 2000 UT     R      1 sigma
--------------------------------
  27.8547       19.414    0.015
  27.8594       19.428    0.011
  27.8639       19.411    0.011
  27.8684       19.433    0.008
  27.8729       19.437    0.011
  27.8774       19.453    0.010
  27.8820       19.441    0.010
  27.9658       19.618    0.011
  27.9705       19.595    0.014
  27.9750       19.641    0.015
  27.9795       19.609    0.017
  27.9840       19.619    0.021
  28.8356       20.778    0.023
  28.8911       20.834    0.034

These magnitudes show that the object identified as the optical afterglow 
is decaying. The temporal power-law decay index appears to progressively
steepen from -1.2 on Sep 27.85 to -1.85 between Sep 28.2 (GCN #806) and 
Sep 28.9, indicating a 'break' in the lightcurve."