A sample of 47 faint Gigahertz Peaked Spectrum (GPS) radio sources selected from the Westerbork Northern Sky Survey (WENSS) has been imaged in the optical and near-infrared, resulting in an identification fraction of 87 per cent. The R-IR-K colours of the faint optical counterparts are as expected for passively evolving elliptical galaxies

Aims. Recent studies have detected linear polarization in L dwarfs in the optical I band. Theoretical models have been developed to explain this polarization. These models predict higher polarization at shorter wavelengths. We discuss the polarization in the R and I band of 4 ultra cool dwarfs. Methods: We report linear polarization measurements of

We analyzed first optical observations of 17 kyr-old PSR J2021+3651 and its pulsar wind nebula obtained with the 10.4-m Gran Telescopio Canarias (GTC) telescope in the Sloan r' band. In addition, we reanalyzed archival X-ray data obtained with Chandra. The pulsar and the nebula were not detected in the optical down to 27.20 and 24.85 magnitude 3σ

We report recent observational results of some ULXs collected with the 8.2m Subaru and with the ESO VLT telescopes. These observations have provided important information on the (inter-) stellar environments and have allowed to detect the optical counterparts of several ULXs. In two cases spectroscopic observations show stellar HeIIλ4686 optical

We present the first optical polarimetric observations of the runaway microquasar LS 5039. Our results reveal the presence of a large amount (˜5%) of polarized emission towards this binary system. By combining polarimetric and spectroscopic observations of some stars in the field together with available statistical information on the galactic

We present high-resolution observations of the giant extragalactic H II regions NGC 604, NGC 2363, NGC 5461, and NGC 5471, based on observations taken with the ISIS spectrograph on the William Herschel Telescope. We have detected, for the first time, C II and O II recombination lines in these objects. We find that recombination lines give larger C+