SIMBAD references

Interstellar scintillation multi-frequency observations of PSR 0329+54 in the frequency range from 102-MHz to 5-GHz were analysed to estimate the spectrum of interstellar plasma inhomogeneities in the direction of this pulsar. Based on the theory of diffractive scintillation, the composite structure function of phase fluctuations covering a large range of turbulence scales was constructed. We found that the spectrum is well described by a power law with n=3.5 for scales from 10⁶ to 10⁹m, which differs from the value known for a Kolmogorov spectrum. We can, however, within the accuracy of our data not exclude a Kolmogorov spectrum. It became also clear that angular refraction of emission must be taken into account to fit the data points at all observing frequencies. The size of the irregularities responsible for the angular refraction is estimated to be about 3x10¹³m. They can be identified with clouds of neutral hydrogen that can be considered as holes of electron density.