Analysis of instantaneous spectra of a complete sample of flat-spectrum radio sources

The results of observations of a complete sample of radio sources with spec tral indices alpha > -0.5 (S proportional to nu(alpha)) are presented. The sample was selected from the Zelenchuk Survey at 3.9 GHz and contains all s ources with declinations 4 degrees-6 degrees, Galactic latitudes /b/ > 10 d egrees, and 3.9-GHz fluxes > 200 mJy. Spectra at 0.97-21.7 GHz were obtaine d for all 69 sample sources. The spectra were classified, and a correlation between variability amplitude and spectrum shape was found. The spectra we re separated into extended and compact components. The distribution of spec tral indices a for the extended components coincides with the distribution for sources with power-law spectra. The correlation between the luminosity and frequency of the peak flux density is confirmed. This correlation is du e to the fact that the distribution of source linear dimensions does not de pend on luminosity. (C) 2000 MAIK "Nauka/Interperiodica".