A consistent analysis, based on non-LTE codes with sphericity and mass loss,of different ionization species in the far-UV and UV spectra of O-type starsallowed us to constrain the long-time uncertain ionization equilibrium in thestellar winds, to quantify the role of soft X-rays from shocks and to reconcileotherwise discrepant UV line diagnostics

Aims:We present a new automatic code (ARES) for determining equivalent widths of the absorption lines present in stellar spectra. We also describe its use for determining fundamental spectroscopic stellar parameters. Methods: The code is written in C++ based on the standard method of determining EWs and is available for the community. The code

We have developed a method to measure the mirror reflectivity of telescopes. While it is relatively easy to measure the local reflectivity of the mirror material, it is not so straightforward to measure the amount of light that it focuses in a spot of a given diameter. Our method is based on the use of a CCD camera that is fixed on the mirror dish

We report time-resolved photometry of the optical counterpart to the black hole candidate SWIFT J1753.5-0127 (Palmer et al. 2005, ATel #546: Halpern et al. 2005, ATel #549). After its discovery, this source has remained in the low/hard state and bright at optical/IR wavelengths. Our analysis indicates that this X-ray transient is a short orbital

We present the first spectroscopy study of massive stars in NGC55. The data, taken with VLT-FORS2 allow us to provide spectral classification for 200 objects located throughout the galaxy. From this sample, suitable B-type supergiants are chosen for subsequent higher resolution spectroscopic observations that will enable a quantitative study. The

We report on the results from an ongoing programme aimed at testing Newton's law of gravity in the low acceleration regime using globular clusters. We find that all clusters studied so far behave like galaxies, that is, their velocity dispersion profiles flatten out at large radii where the acceleration of gravity goes below 10 8 cm s 2, instead of