We used archival multi-band Hubble Space Telescope observations obtained with the Wide Field Camera 3 in the UV-optical channel to present important new observational findings on the color-magnitude diagram (CMD) of the Galactic globular cluster ω Centauri. The UV WFC3 data have been coupled with available Wide Field Channel/Advanced Camera for

The new transient LMXB in NGC 6440 (CXOGlb J174852.7-202124; Atel #2139) is declining rapidly. RXTE observed NGC 6440 on July 30 (18:47 to 19:26 TT). The PCA top-layer spectrum is well fit with an absorbed power-law of photon index 2.2+-0.1, with N_H set to 6e21 cm^-2 (as found by Chandra). The inferred 0.5-10 keV luminosity is 4e35 ergs/s, a

The low surface brightness usually associated with nebulae mixing with the ISM has long been a substantial obstacle in the observation and statistical study of these interactions. Thanks to the detection capability of the INT Photometric H-alpha Survey (IPHAS), in terms of sensitivity and imaging resolution, we were able to detect and select tens

A lightcurve of comet 6P/d'Arrest from R-band CCD images taken at La Palma 2.52 m NOT telescope is presented. The lightcurve shows noticeable periodic changes in brightness produced by rotational modulation. The periodogram analysis of the lightcurve shows a peak with a confidence level exceeding 99.9% at 3.336 h. Assuming an elongated nucleus, the

Context: The compact association Cygnus OB2 is known to contain a large population of massive stars, but its total mass is currently a matter of debate. While recent surveys have uncovered large numbers of OB stars in the area around Cyg OB2, detailed study of the optically brightest among them suggests that most are not part of the association

Recent observational and theoretical investigations of the sun and sunlike stars and of galactic structure and evolution are discussed in reviews and reports. Topics addressed include sunspot-group decay rates for 1874-1976, photometry and spectroscopy of solar granulation along the polar axis and equator, the quiescent radio emission of RS CVn