Empleando imagenes adquiridas con la cámara de alta resolución ACS (Advanced Camera Survey) del Telescopio Espacial Hubble (HST), hemos hecho un cartografiado de la emisión en Halpha en las galaxias M51 y NGC 4449, encontrando y analizando una pobación completo de regiones HII. Para las regiones HII de ambas galaxias analizamos la función de

Wide-field (~33'x33') proper motion catalog for nearly 360000 stars centered around Omega Cen center. Calibrated and sky concentration corrected UBVRCIC wide-band photometry plus a narrow-band filter centered on Halpha. Membership probability determination with two different, complementary methods. (2 data files).

Our neighbouring galaxy M31 (Andromeda), located 780 kpc away, offers a unique opportunity to study the X-ray population of a galaxy similar to the Milky Way. We have concentrated our monitoring campaign on following the X-ray activity of the stellar-mass black hole candidates, XRNe (X-Ray Novae), in the central region of M31. Observations are made

XTE J1701-407 is a new transient X-ray source discovered on 2008 June 8. More than one month later, it showed a rare type of thermonuclear explosion: a long type I X-ray burst. We report herein the results of our study of the spectral and flux evolution during this burst, as well as the analysis of the outburst in which it took place. We find an

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We present the results of a multisite photometric campaign on the pulsating B-type hot subdwarf star Balloon090100001 (Bal09). The star is one of the two known hybrid hot subdwarfs with both long- and short-period oscillations, theoretically attributed to g and p modes. The campaign involved eight telescopes with three obtaining UBVR data, four B