VLBI Observations of OH Masers with the S-2 Recording System

We present results from the first intercontinental test of the Canadian S-2 recording system. In 1993 November a number of continuum and OH maser sources were observed with bandwidths of 16 and 4 MHz, respectively, and two-bit sampling. In this report we concentrate on the OH maser sources for which 1665- and 1667-MHz transitions were detected. Continuum results will be reported separately. The measured upper limits on the scattered angular size are an order of magnitude lower than the average scattered size calculated from the Galactic model of scattering distribution by Cordes, Weisberg & Boriakoff. Our results are consistent with a patchy distribution of the scattering material in the Galactic disc, with some OH masers located in regions of low interstellar scattering.