We report optical and infrared photometric and spectroscopic observations that identify the counterpart to the 358.6-s X-ray transient pulsar SAX J2103.5+4545 with a moderately reddened V=14.2 B0Ve star. This identification makes SAX J2103.5+4545 the Be/X-ray binary with the shortest orbital period known, Porb= 12.7 days. The amount of absorption

We present a comprehensive and reliable statistics of 200 mbar wind speeds at the Canary Islands based on long term climate diagnostics archive data and balloon measurements. The results demonstrate the remarkable stability of the Canarian sky, with low mean values of V200 = 22.12 ms-1 at the Roque de los Muchachos Observatory (ORM, La Palma, Spain

A study of the correlation of the morphology of a complete sample of 255 galactic planetary nebulae (PNe) with their nebular parameters is presented here. Projection effects were taken into account. PNe were classified according to the following scheme: round (R, 25%), elliptical (E, 58% of the sample), and bipolar (B, 17%). Bipolars include the

The current designs of the majority of ELTs envisage that at least the primary mirror will be segmented. Phasing of the segments is therefore a major concern, and a lot of work is underway to determine the most suitable techniques. The techniques which have been developed are either wave optics generalizations of classical geometric optics tests (e

We have determined abundances in the secondary stars of the black hole X-ray binary A0620-00 and the neutron star Binary Cen X-4.

Using a high-resolution spectrum of the secondary star in the black hole binary A0620-00, we have derived the stellar parameters and veiling caused by the accretion disk in a consistent way. We have used a χ2 minimization procedure to explore a grid of 800,000 LTE synthetic spectra computed for a plausible range of both stellar and veiling