We have completely mapped the Galactic globular cluster NGC 1851 with large-field, ground-based VI CCD photometry and pre-repair HST/WFPC1 data for the central region. The photometric data set has allowed a V vs. (V-I) colour-magnitude diagram for ~ 20500 stars to be constructed. >From the apparent luminosity of the horizontal branch (HB) we derive

En esta Tesis Doctoral, tras una introducción sobre las estructuras magnéticas solares, en particular aquéllas no resueltas espacialmente, sus observaciones y técnicas de diagnóstico, y el problema del transporte de radiación polarizada en presencia de campo magnético, se presenta un nuevo código de inversión de la ecuación de transporte radiativo

IAUC 6902 available at Central Bureau for Astronomical Telegrams.

We report on the results of optical follow-up observations of the counterpart of GRB970508 between 7 hours and 100 days after the event. Multi-colour U, B, V, Rc and Ic band observations were obtained during the first three consecutive nights. The Rc light curve rises to a maximum 1.8 days after the burst and after this declines with a power law

Mean-field theory in its kinematic form with the quasi-linear approximation is widely used for the modelling of the transport of weak magnetic fields in turbulent media. The validity of this approach to real astrophysical flows is discussed. Numerically evaluating the turbulent electromotive force using Lagrangian analysis for a set of simple

Using the Nordic Optical Telescope, La Palma, Spain, optical studies of OT/GRB970508 were initiated 3 hours 5 minutes after the high energy event (This appears to be sooner than achieved elsewhere, for any optical transient). The OT was clearly detected in the earliest images. The last observation was done August 13-15, i.e. 95-97 days after the