  Observations of the PSR B1259-63/SS2883 binary system using the CANGAROO-II
Cherenkov telescope are reported. This nearby binary consists of a 48msec radio
pulsar in a highly eccentric orbit around a Be star, and offers a unique
laboratory to investigate the interactions between the outflows of the pulsar
and Be star at various distances. It has been pointed out that the relativistic
pulsar wind and the dense mass outflow of the Be star may result in the
emission of gamma rays up to TeV energies. We have observed the binary in 2000
and 2001, 47 and 157 days after the October 2000 periastron. Upper limits at
the 0.13--0.54 Crab level are obtained. A new model calculation for high-energy
gamma-ray emission from the Be star outflow is introduced and the estimated
gamma-ray flux considering Bremsstrahlung, inverse Compton scattering, and the
decay of neutral pions produced in proton-proton interactions, is found to be
comparable to the upper limits of these observations. Comparing our results
with these model calculations, the mass-outflow parameters of the Be star are
constrained.
