EL PRESENTE TRABAJO SE HAYA DIVIDIDO EN DOS PARTES CLARAMENTE DIFERENCIALES AUNQUE ESTRECHAMENTE RELACIONADAS. EN LA PRIMERA SE DESARROLLA UN CONJUNTO DE PARAMETROS CAPACES DE CARACTERIZAR ESTRUCTURAS PRESENTES EN LOS PERFILES FOTOMETRICOS ACIMUTALES DE GALAXIAS, APLICANDOLOS A LA ESTRUCTURA ESPIRAL DE LAS GALAXIAS NGC 1832 Y NGC 7479 EN LAS BANDAS

The authors have determined the masses and orbital parameters for the galaxies in the strongly interacting binary NGC 4782/4783 by finding a numerical simulation of the collision that accurately represents all of the observed properties of the system. With this simulation, the authors have completely determined the three-dimensional orientation and

EL DESARROLLO DE LA HELIOSISMOLOGIA SE HA BASADO EN TECNICAS ESPECTROMETRICAS, MIDIENDO LA VARIACION DE LA VELOCIDAD SUPERFICIAL DEL SOL. A TRAVES DEL ESTUDIO DE LOS MODOS ACUSTICOS SOLARES PERO MEDIDOS COMO VARIACIONES EN LA LUMINOSIDAD SE PUEDE OBTENER UNA INFORMACION COMPLEMENTARIA DE GRAN IMPORTANCIA ASI COMO MEJORAR LAS TECNICAS FOTOMETRICAS

Johnson B CCD photometry of quasars and other active nuclei were obtained with the 1-m and 2.5-m reflectors of the Roque de los Muchachos Observatory in the Canary Islands between 1986 and 1987. Data are presented for PKS 1538+149, 3C 345, 3C 351, and BL Lac. Error sources are discussed, and it is noted that at least part of the error is due to

In this paper the approximate Lambda-Operator (ALO) developed by Olson, Auer and Buchler (OAB, 1986) is inspected from a more mathematical standpoint and compared to presently most commonly applied ALOs. For simple model calculations,it is shown that OAB's operator which contains no arbitrary parameter always works close to the optimum convergence

A statistical study of the decay of sunspots and sunspot groups is carried out using data contained in the Greenwich Photoheliographic Results. The period studied spans more than six decades, namely from 1874 to 1939. The adequacy of exponential, quadratic and linear decay laws to the area decay data is considered. The dependence, or otherwise, of