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

Observations of the pulsar B1642–03 were carried out with the ground-space interferometer Radioastron during the implementation of the key scientific program of the project. The observations were conducted on September 8, 2013 at frequencies 316–332 MHz. The Westerbork Synthesis RT (WSRT) was used as a ground arm of the interferometer. The baseline projections of the interferometer changed during the observations approximately from 10 000 km to 20 000 km, and the positional angle of the baseline changed almost for 50X. This configuration made it possible to estimate the angular diameter of the scattering disk in different positional angles. It was found that 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 indicates a possible irregular structure of the scattering disk, which may be due to lensing of radio waves when passing through the Stromgren zone near the star ζ Oph.