Anisotropic Scattering of the Radio Emission in the Direction to Pulsar B1642–03

Pulsar B1642–03 has been observed with the Radioastron ground-space interferometer during the implementation of the Key Science Program of the project. Observations were made on September 8, 2013, in the 92-cm band at frequencies 316–332 MHz. The Westerbork Synthesis RT (WSRT) has been used as a ground arm of the interferometer. The baseline projections of the interferometer have changed during the observations approximately from 10 000 to 20 000 km, and the positional angle of the baseline has changed almost for 50°. This configuration has made it possible to estimate the angular diameter of the scattering disk in different positional angles. It has been found that the shape of the scattering disk can be presented in the form of an ellipse with an axial ratio of 2 : 1. Comparison of the angular size of the scattering disk and the delay time of scattered rays has indicated a possible irregular structure of the scattering disk, which may be due to lensing of radio waves when passing through the Stromgren zone near star $$\zeta $$ Oph.