On the east-west asymmetry of the central residual intensities and other fraunhofer line parameters

Fraunhofer line parameters of the Sun are investigated from the centre to the limb of the solar disk. Observational profiles of 13 Fraunhofer lines in two spectral ranges (6880 and 6980 A) were derived from the photoelectric tracings taken with the doublepass (''double monochromator'') solar spectrograph of the Pulkovo Observatory. The tracings were made in Summer and Autumn 1963 and cover the minimum of the 19 solar 11--year cycle and the beginning of the new cycle. The observations of both the east and west limbs with the spectrograph slit perpendicular to the radius of the solar disk became possible up to μ=cos THETA=0.158 (THETA is the angle between the line of sight and the solar radius at the point of observation). The tracings of some Fraunhofer lines showed systematic and real differences in profile parameters at the east and west limbs. In particular, central residual intensities, which can be measured more accurately than the halfwidth and the equivalent width of an absorption line, are at the same μ, slightly higher at the west limb of the solar disk than at the east one. For the group of lines under consideration, this effect becomes stronger with the increase of lines' intensities. It is noted, that this ''east-west asymmetry'' of the Fraunhofer line parameters may be due to a horizontal motion of matter of the large-scale field of the solar atmosphere