A statistical analysis of the modulation index (m) distribution along the galactic latitude for different samples of variable extragalactic radio sources has been performed in a wide frequency range from 80 MHz to 37 GHz. The distributions of the median m values have demonstrated a striking monotony at all frequencies from meters to millimetres in spite of a considerable scattering in the individual m values. Some correlation of m with the galactic latitude was known for low frequency variability and flickering. It was explained by refraction interstellar scintillation (RISS). The same distribution of m is unexpected for centimetre and millimetre wavelengths. The galactic latitude distribution of m obtained are compared with a simple RISS theory It is shown that the difference between the observed data and the simple theory of RISS is significant at low galactic latitudes |b| ≤ 15° ÷ 30 ° almost for all frequencies considered. Some speculations about the galactic latitude distribution discovered are given in the frame of interstellar scintillation. One of them is the flattening of the electron density fluctuation spectrum at low galactic latitudes.

We report an asymmetry in the distribution of low frequency variable (LFV) radio sources towards the centre-anticentre regions of our galaxy. The study is based on 15 years' monitoring of a large sample of sources observed with Culgoora Array at 80 and 160 MHz. This asymmetry is in marked contrast with the symmetrical distribution of non-variable sources from the same sample. Median values of the corresponding modulation indices on both short and long time scales also show a statistically significant increase towards the Galactic centre compared with the anticentre region. These results strongly suggest that LFV has an interstellar origin and that the most likely mechanism is refractive scintillation. Key Words: Extra-galactic radio sourcesradio source variabilityinterstellar matter

A 3.4-cm wavelength radiometer aboard the Mars 2 and 3 orbiters observed the brightness temperature due to planetary thermal emission in two orthogonal polarizations as a function of position on Mars. Preliminary results for two orbits of Mars 3 show a correlation between subsurface temperature and dielectric constant, interpreted as an effect of porosity.