We present time-resolved spectroscopy and circular spectropolarimetry of the SW Sex star RXJ1643.7+3402. We find significant polarization levels exhibiting a...

A NLTE-analysis is presented of high S/N spectra of the optical component of the standard massive X-ray binary Vela X-1. In combination with the orbital...

We present the first detection of the mass donor star in the prototype X-ray binary Scorpius X-1. Phase-resolved spectroscopy revealed narrow emission line...

Cygnus X-2 is one of the brightest and longest known X-ray sources. We present high-resolution optical spectroscopy of Cyg X-2 obtained over 4 yr, which gives...

We present a dynamical study of the intermediate polar cataclysmic variable YY Dra based on time-series observations in the K band, where the donor star is...

We have obtained high- and intermediate-resolution optical spectra of the black hole candidate Nova Scorpii 1994 in 1998 May/June, when the source was in...

We report intermediate resolution H alpha spectroscopy of the black hole candidate Nova Muscae 1991 during quiescence. We classify the companion star as a K3...

We present the results of the study of visible (UBVRIZ) intra-night microvariability in the blazar OJ 287. Useful observations (at least four integrations in a...

Polarization measurements of the microquasar Cygnus X-1 exist at γ-ray, X-ray, ultraviolet, optical and radio frequencies. The γ-ray emission has been shown to...