Context. Twilight studies have proved to be important tools for analyzing the atmospheric structure with interesting consequences on the characterization of astronomical sites. Active discussions of this topic have started again recently in connection with the evaluation of Dome C, Antarctica, as a potential astronomical site and several site-testing experiments, including twilight brightness measurements, are being prepared. Aims. The present work provides the first absolute photometric measurements of twilight sky brightness for ESO-Paranal (Chile). They are meant both as a contribution to the site monitoring and as reference values in the analysis of other sites, including Dome C. Methods. The UBVRI twilight sky brightness was estimated on more than 2000 FORS1 archival images, which include both flats and standard star observations taken in twilight and covering a Sun zenith distance range 94• -112• . Results. The comparison with a low-altitude site shows that Paranal V twilight sky brightness is about 30% lower, implying that some fraction of multiple scattering has to take place at an altitude of a few km above sea level.

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The paper contains the results of wide-angle polarization camera (WAPC) measurements of the twilight sky background conducted in summer 2011 and 2012 at 55.2°N, 37.5°E, southwards from Moscow. The method of single scattering separation based on polarization data is suggested. The obtained components of scattering matrixes show the domination of Rayleigh scattering in the mesosphere for all observation days. It made possible to retrieve the altitude distribution of temperature in the mesosphere. The results are compared with the temperature data by TIMED/SABER and EOS Aura/MLS instruments for nearby dates and locations.

Abstract. The work is devoted to the analysis of the surface photometric observations of two total lunar eclipses in 2004. The lunar surface relative brightness distribution inside the umbra was used to retrieve the vertical distribution of aerosol extinction of the solar radiation expanding by a tangent path and its dependence on the location at the limb of the Earth. The upper altitude of troposphere aerosol layer was estimated for different latitude zones. The correlation between additional aerosol extinction in the upper troposphere and cyclones was investigated.