Esta tesis presenta un estudio de la población de estrellas variables en cinco galaxias aisladas del Grupo Local (GL), basado en imágenes obtenidas con el telescopio espacial Hubble (HST). Se discuten sus características en el contexto de la historia de formación estelar (HFE) de las galaxias anfitrionas. Se observaron Cetus, Tucana, IC,1613, LGS,3

We present phase resolved optical spectroscopy and photometry of V4580 Sagittarii, the optical counterpart to the accretion powered millisecond pulsar SAX J1808.4-3658, obtained during the 2008 September/October outburst. Doppler tomography of the NIII λ4640.64 Bowen blend emission line reveals a focused spot of emission at a location consistent

We present accurate new ultraviolet and optical BVI photometry for the Galactic globular cluster NGC 2808 based on both ground-based and archival Hubble Space telescope imagery. From this we have selected a sample of ~2000 Horizontal Branch (HB) stars; given the extensive wavelength range considered and the combination of both high angular

After three years since the beginning of operation, the MAGIC telescope could observe several GRB events in the prompt and early afterglow phase. Thanks to its innovative design, the telescope could promptly react to incoming GCN alerts and rapidly slew to the burst coordinates within a typical delay of 50 seconds, performing observations with an

Ongoing and future optical and near-infrared surveys focused on the study of the Galactic plane are briefly presented. Their potential is illustrated by the first results from IPHAS, the INT Photometric Hα Survey of the Northern Galactic Plane.

The ALHAMBRA survey aims to cover 4 deg2 using a system of 20 contiguous, equal width, medium-band filters spanning the range 3500 Å-9700 Å plus the standard JHKs filters. Here we analyze deep near-IR number counts of one of our fields (ALH08) for which we have a relatively large area (0.5 deg2) and faint photometry (J = 22.4, H = 21.3, and K = 20