An attempt is made to confirm the observation of Allen (1980) of a 3.3-micron emission feature attributed to thermal dust emission in the quasar 3C 273. Spectrophotometric observations of 3C 273 were obtained on May 18, 19 and 24 with the 1.5-m telescope of the Mount Lemmon Observatory. No evidence is found for the 3.3-micron feature in excess of 7

Maps in the CO (J = 2-1) line of the southern H II region complexes Carina Nebula and G333.6-0.2/RCW 106 are presented and discussed. Results for the Carina Nebula indicate a complicated spatial structure; an extended molecular cloud appears to be wrapped partly around the brightest parts of the H II region (Car I and Car II). The situation in

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