Improved estimates of interstellar scattering through the inner galaxy

Forty-one radio sources near the galactic plane (|b|<30) have been studied for interplanetary scintillations at 1420 and 327 MHz. Eight of these sources showed scintillations at 1420 MHz indicating the presence of compact components. At 327 MHz, however, only one of these sources showed detectable scintillation. We have examined possible explanations for the absence of scintillations at 327 MHz and suggest that angular broadening of radio sources due to interstellar scattering is the most likely. From our observations we have set lower limits on the interstellar scattering towards these sources. (author)