Modern Acquisition and Guiding systems provide a range of services with the aim of optimizing telescope performance. These include wavefront sensing for active optics, fast guiding and measurement of seeing. On a segmented-mirror telescope, the Acquisition and Guiding system may also be expected to provide measurements of the piston errors between

El estudio de las galaxias enanas, especialmente de las compactas azules, ha sido de especial interés en las últimas décadas despues del exceso observado de estos objetos a z intermedios, lo cual puede ser interpretado como evidencia de la existencia de enanas con formación estelar alta en otra época y que actualmente han desaparecido. Especial

We have extended our evolutionary synthesis models for Star Forming Regions to the γ-ray domain. Applying different yields to the resulting synthetic populations, we obtain lightcurves of γ-ray line emission due to the radioactive decay of stellar nucleosynthesis products, such as 26Al and 60Fe. We present here this time evolution and the

We present results of narrow-band (Hα and adjacent continuum) and broad-band (U, B and V) optical CCD imaging together with high- and intermediate-resolution optical spectroscopy for a sample dwarf and/or irregular Wolf-Rayet (WR) galaxies with absolute B magnitudes in the range -14 to -22 mag, taken from the catalogue of Conti (1991). We find that

We present analytic formulae that approximate the evolution of stars for a wide range of mass M and metallicity Z. Stellar luminosity, radius and core mass are given as a function of age, M and Z, for all phases from the zero-age main sequence up to, and including, the remnant stages. For the most part we find continuous formulae accurate to within

IAUC 7468 available at Central Bureau for Astronomical Telegrams.