We report here on multifrequency radio observations of the pulsed emission from PSR B1259–63 around the time of the closest approach to its B2e companion star .
There was a general increase in the pulsar ’ s dispersion measure and scatter broadening , and a decrease in the flux density towards periastron although changes in these parameters were seen on timescales as short as minutes .
The pulsed emission disappeared 16 days prior to periastron and remained undetectable until 16 days after periastron .

The observations are used to determine the parameters of the wind from the Be star .
We show that a simple model , in which the wind density varies with radius as r ^ { -2 } , provides a good fit to the data .
The wind is clumpy with size scales \leq 10 ^ { 10 } cm , densities of \sim 10 ^ { 6 } cm ^ { -3 } and a velocity of \sim 2000 km s ^ { -1 } at a distance of 20 - 50 stellar radii .
We find a correlation between dispersion measure variations and the pulse scattering times , suggesting that the same electrons are responsible for both effects .