The role of refractive interstellar scintillation in the low frequency variability of extragalactic radio sources

A statistical analysis is presented of the 408 MHz flux density time series of 39 extragalactic radio sources, to study the role of refractive interstellar scintillation in the decimeter wavelength variability of compact extragalactic radio sources. It is found that the product of the scintillation index and the variability timescale is systematically larger for sources at lower galactic latitudes. This variation is obscured by much larger random variations. Possible explanations of these results are discussed.