Non-LTE calculations of H-alpha line profiles are presented and applied to derive rotational velocities from high-resolution spectra of DA white dwarfs. This paper extends recent work by Pilachowski and Milkey (1984, 1987) to southern hemisphere objects and confirms their findings that all white dwarfs seem to be slow rotators. Of the seven objects

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EN ESTE TRABAJO OBTENGO Y ANALIZO ESPECTROS DE LOS PARAMETROS DE STOKES V E I TOMADOS SOBRE PUNTOS BRILLANTES (EN CAII K) DE FACULAS Y RED FOTOSFERICA. PRESTO ESPECIAL ATENCION A LA INFLUENCIA DE LA POLARIZACION INSTRUMENTAL. POR ESTE MOTIVO NECESITO CALCULAR LA MATRIZ DE MUELLER DEL TELESCOPIO VGT DEL OBSERVATORIO DEL TEIDE. PONGO UN LIMITE

Monochromatic extinction coefficients at four wavelengths have been obtained over a period of more than two years at the Observatorio del Teide (Izaña Tenerife) using a full disc, direct sunlight, quadruple photometer devoted to the detection of integral luminosity oscillations of the Sun. The mean extinction coefficients (0.13 at 500 nm) show a

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CCD photometry of resolved dwarf irregular galaxies was obtained with the 4-m Cerro Tololo Interamerican Observatory telescope in February 1985. BV data from 77 stars in DDO 187 are used to infer a distance modulus of 28.2 + or - 0.6, placing this galaxy out of the Local Group, at a distance of 4.4 + or - 1.0 Mpc. In the second part, UBV photometry