[en] Observations carried out at the radiometric station of Bruncu Spina (Sardinia, altitude 1825m) for the determination of turbidimetric characteristics are analysed and discussed. Diurnal evolution of the turbidimetric parameters α and β is emphasize. The values of the turbidity coefficient β show particularity low aerosol concentration in the site. A comparison among turbidimetric characteristics of different radiometric stations confirms the existence of a correletion between the radius of aerosol particles and the altitude of the sites

[en] The observational data on photospheric faculae are briefly considered. Difficulties, encounted by homogeneous models in explaining the whole set of observational data, are outlined. A possibility of constructing an inhomogeneous model of a facula, in which a filament consists of denser facula granulae with photospheric matter between them, is considered. It is supposed that facula granulae are more opaque than the undisturbed photosphere, then the radiation from hotter layers, which go through the transparent photosphere, should go out in lateral directions from facula granulae. To explain the observed brightness excess of facula filaments in the continum, it is sufficient that, e.g., at equal depths, the density in a facula by twice that in the photosphere. Therby, no surface overheat exceeding 130 K is required. In a similar way, the observed line weakening can be explained

[en] New phase curves for Saturn's rings at an intermediate tilt angle B approx.17 ⁰ are presented. Quantitative results for each of the A and B rings are reported in terms of the opposition effect, phase coefficient, and best logarithmic fit to the phase curve. In each of the four colors, there is no significant difference between the shape of the phase curves for the two rings, as was also found in B and V by Franklin and Cook (1965). The shape of the green phase curves are well determined and consistent with earlier observations taken at a maximum tilt angle. A simple, four-parameter multiple scattering model of the rings (including the effect of mutual shadowing) is shown to be consistent with the observations. The derived parameters are also consistent with the detailed analyses of the phase curves at maximum tilt angle (Kawata and Irvine, 1975) and of the variation of brightness of the rings as a function of tilt angle (Esposito and Lumme, 1977). In this multiple scattering model, the difference in the phase curves for different colors can be explained by a variation in the single scattering albedo with wavelength. The observations allow the particles to have the same composition in both the A and B rings, so that their different photometric behavior is explained by differences in optical depth and volume density in the two rings. In conjunction with earlier studies, these results provide strong support for the classical model of the rings as a layer many particles thick

[en] We have analysed 340 spectra of beam irradiance at normal incidence corresponding to 42 cloudless days during the period from July 1993 to June 1995. The spectra were obtained at ground level in Valencia, Spain, suing a Li-cor 1800 spectro radiometer and have been used to determine the aerosol optical depth, τ_aλ, for the 400-670 nm band. This parameter exhibited large temporal and spectral (high turbidities, wavelengths near the ultraviolet). (Author) 18 refs

[en] The system EE Aqr has been observed in UBV colours. A consistent set of orbital elements and a slightly improved period of 0sup(d). 5089954 have been obtained. The eclipse is partial and variability is of β Lyrae-type. The colour of the components has been determined. (Auth.)

[en] A model of the phenomenon which leads to the brightness attenuation of Is(A) stars is discussed. Two hypotheses have been used. 1. The appearance of some absorptive matter over the star-disk causes the light absorption and optical depth of matter tau increases from 0 up to tausub(max). 2. Short-wave excess of radiation emerges in the zone lying over the region of light absorption. The model proposed allows to account for a multiplex relation between V magnitudes and B-V, U-B colours that have been shown by some rapid irregular variables. The results of numerical calculation were compared with the observed V, B-V, and U-B magnitudes of RZ Psc which have been obtained in 1972-1975. Calculated colours B-V and U-B coincided with the observed ones. The UBV intensities of short-wave excess and values tausub(max) as well as the extinction low of absorptive matter xsub(lambda) approximately (1/lambda)sup(1.4) are found

[en] The homogeneous prominence of spherical form is considered. The isotropic line scattering, complete frequency redistribution and the Doppler line profile are assumed. It is supposed that primary sources of radiation are distributed uniformly through the medium. The method of determination of optical radius of prominence by means of the observed line profiles, developed for the case of pure scattering, in the earlier paper, is generalized for the case of any lambda photon survival probability. The modification of the method is elaborated, where the line equivalent widths instead of central intensities are used

[en] The map of the surface brightness B of the galaxy is constructed and the standartization of brightness in the U, B, V-system of the photographic measurements with the help of comparison with the photoelectric ones is performed. The distribution of colour over the galaxy disc is obtained after supplementary correction of zero points of colour indices, which were measured earlier. The photometric centre of brightness of M 82 is close to the dynamic centre. The results are necessary for the construction model of the galaxy M 82. The discovered phenomenon of the asymmetry of the colour distribution in the southern and northern parts of M 82 is discussed on the basis of the rough three-component model of the galaxy. The values of the optical thickness of dust in function of the distance from the centre along the major axis of the galaxy was obtained

[en] By using a suitable target geometry, opacity of X-ray emission has been measured on an aluminium laser created plasma. By means of simple theoretical models optical depths are inferred and seem to be in accordance with Stark and Doppler line broadening

[en] Physical conditions of the magnetosphere of pulsars have been investigated. For the P 0531 object the temperature of magnetosphere is 5x10⁴K, and for other pulsars it varies from 10⁴ to 10⁷K at the end of magnetosphere. For the P 0531 a magnetospheric plasma is sustained in such a hot state by the Joule heat arising from drift currents. In the case of other pulsars the initial part of the magnetosphere is heated by star radiation, and the remaining major portion - by drift currents