The Nuclear Spectroscopic Telescope Array (NuSTAR) enables detailed high-energy X-ray observations from 3─79 keV, but its performance can be constrained by...

We report on a detailed optical spectroscopic follow-up of the black hole (BH) transient MAXI J1820+070 (ASASSN-18ey). The observations cover the main part of...

We present a novel strategy to uncover the Galactic population of quiescent black holes (BHs). This is based on a new concept, the photometric mass function...

The advent of the new generation of X-ray telescopes yielded a significant step forward in our understanding of ionised absorption generated in the accretion...

We have identified a new intermediate polar, HS 0943+1404, as part of our ongoing search for cataclysmic variables in the Hamburg Quasar Survey. The orbital and...

We present a spectrophotometric study of short-term optical variability in the quiescent black hole X-ray transient V404 Cyg. This includes two nights of high...

Swift J1357.2−0933 is a transient low-mass X-ray binary hosting a stellar-mass black hole. The source exhibits optical dips and very broad emission lines during...

Millisecond radio pulsars are neutron stars that have been spun up by the transfer of angular momentum during the low-mass X-ray binary phase. The transition...

We present infrared photometry of the Galactic bulge X-ray binary systems GX 13+1 and GX 17+2 obtained in 1997 July and August using OSIRIS on the 1.8 m Perkins...