  CCD Johnsons BV and Cousins RI photometric magnitudes are determined for 20
stars in the field of GRB 000926. Using them as calibrators, B and R band light
curves are constructed of the afterglow from ours and other published
observations. They show a steepening of the flux decay, from a decay constant
of 1.4+/-0.1 to 2.6+/-0.06 at about 1.7 days after the burst. Attributing this
break to the onset of sideways expansion of a jet-like ejecta, we estimate an
initial jet opening angle of ~0.14 radian, and a burst energy of ~10^51 erg. We
construct the X-ray-optical-near infrared spectrum of the afterglow and derive
a spectral index of ~ -0.9. From the spectrum we also estimate that the source
has a rather large intrinsic extinction, amounting to E(B-V)=0.36+/-0.02.
