The persistent low-luminosity neutron star X-ray binary 4U 1812-12 is a potential member of the scarce family of ultra-compact systems. We performed deep...

We present long-slit, optical spectra of the merging system Arp220, obtained using the William Herschel Telescope (WHT) on La Palma. These data were taken as a...

We investigate the spectroscopic optical properties of gamma-ray sources detected with high significance above 50 GeV in the Third Catalog of Hard Fermi-LAT...

Context. Blazars are the most numerous class of high-energy (HE; E ∼ 50 MeV−100 GeV) and very high-energy (VHE; E ∼ 100 GeV−10 TeV) gamma-ray emitters...

Active galactic nuclei (AGNs) make up about 35 per cent of the more than 250 sources detected in very high-energy (VHE) gamma rays to date with the imaging...

Context. Blazars, which include BL Lacs and flat-spectrum radio quasars, represent the brightest persistent extragalactic sources in the high-energy (HE; 10 MeV...

As part of an investigation into the high-mass end of the initial mass-final mass relation we performed a search for new white dwarf members of the nearby (172...

We present a time-resolved spectrophotometric study of the optical variability in the quiescent soft X-ray transient A0620-00. Superimposed on the double-humped...

We present a detailed spectroscopic investigation, spanning four winters, of the asymptotic giant branch (AGB) star IRAS 02091+6333. Zijlstra & Weinberger (cite...