Mg II resonance lines at 2800 A were studied in the spectra of F and G main sequence stars, observed with the IUE satellite in high resolution mode. Correlation with other chromospheric indicators were investigated and a search was conducted for the best candidates to continue further studies of differential rotation. An attempt has been made to

Near infrared observations between 0.7 and 5 microns of the irregular H II region S 146 are reported. A source found near the center of the nebula is identified as the exciting star. It is suggested that it is a young hot star of spectral type O 7 V with a visual extinction of approximately 16 magnitudes. S 146 is very similar to the axial

A method for determining the variation in the density of dust particles is described. Here, the altitude above the symmetry plane of interplanetary dust is arrived at through ground-based observations. In describing the method, the geometric relation between sun-particle and particle-observer distances is given. It is intended to use measurements

SE DISEÑA Y CONSTRUYE UN ESPECTROFOTOMETRO DE BAJA RESOLUCION EN EL VISIBLE. UN ESTUDIO OBSERVACIONAL DE LA LUZ DEL CIELO NOCTURNO PERMITE DETERMINAR LA EXISTENCIA DE UN UNICO MECANISMO DE PRODUCCION DEL CONTINUO ATMOSFERICO ENTRE 4200 A Y 7000 A. OTRO MECANISMO DIFERENTE ES DOMINANTE HACIE EL INFRARROJO. ESTO PERMITE MEJORAR LOS METODOS DE

SE DESCRIBE UN METODO CON EL CUAL UTILIZANDO SOLO MEDIDAS DE LUMINANCHA SE PUEDEN DETERMINAR LA HOMOGENEIDAD DEL MEDIO Y LAS FUNCIONES DE DENSIDAD Y DE ESPARCIMIENTO. LOS RESULTADOS OBTENIDOS SE UTILIZARON PARA DETERMINAR EL PERFIL QUE PRESENTA LA NUBE AL SER CORTADA POR EL PLANO MERIDIANO

Doppler shifts of the solar Fe line 630.15 nm relative to the terrestrial O2 line 630.2 nm were determined at many positions on the solar disk to investigate the rotation of the solar plasma and locate large-scale plasma motions. The spectrum was measured by a self-scanning linear photodiode array with 128 diodes; and average rotation velocity of