We present a test for the degree of symmetry in the distribution of the Hα brightness along the arms of a sample of spiral galaxies. The test consists of deriving the cross-correlation function of the Hα brightness as a function of curvilinear distance along pairs of opposed arms, after unfolding the arms geometrically. Our results reveal a

En esta memoria se aplican técnicas astrosismológicas a ocho estrellas delta Scuti, en diferentes estados evolutivos y pertenecientes al cúmulo del Pesebre para obtener sus modos propios de oscilación y, a partir de ellos, obtener información tanto sobre la estructura de las estrellas particulare, como sobre las características generales del cúmulo

We present evidences of extended line-emission in the quadruple system Q2237+0305. Using 2D spectroscopy obtained with the fiber based system INTEGRAL in subarcsecond seeing conditions, we have derived intensity maps for the continuum and the emission in the CIII]lambda1909 line. The continuum maps show four distinct compact sources which agree in

We present initial results from a water-vapour monitoring campaign initiated in 1996. A certain amount of caution must still be applied to the interpretation of the water-vapour statistics as a large majority of the data have been taken in summer, or autumn. Continued monitoring is accumulating strong evidence of a seasonal effect, with typically

The velocity field of the nearly face-on galaxy NGC 3631 is derived from observations in the Hα line on the 6-m telescope of the Special Astrophysical Observatory. These optical data are compared with radio observations of this galaxy (Knapen 1997). It is argued that the two-armed spiral structure of NGC 3631 has a wave nature, and that the

It is planned to include adaptive optics as an integral part of the 10-m Gran Telescopio Canarias. Preliminary scientific requirements have been drawn up, and it is necessary to identify systems which will satisfy these requirements. The approach adopted here is to use the LACE program to model the adaptive-optics system. The program provides for