Related papers: A preliminary timing analysis of two intermediate …

We present 20 epochs of optical spectroscopy obtained with the GTC-10.4m telescope across the bright discovery outburst of the black hole candidate Swift J1727.8-162. The spectra cover the main accretion states and are characterised by the…

Phase-resolved spectroscopy of four AM CVn systems obtained with the William Herschel Telescope and the Gran Telescopio de Canarias (GTC) is presented. SDSS\,J120841.96+355025.2 was found to have an orbital period of 52.96$\pm$0.40\,min and…

We report on ground-based optical observations of ten cataclysmic binaries that were discovered through their X-ray emission. Time-resolved radial velocity spectroscopy yields unambiguous orbital periods for eight objects and ambiguous…

[abridged] We report four years of radial velocity monitoring observations of SDSS J080531.84+481233.0 that reveal significant and periodic variability, confirming the binary nature of the source. We infer an orbital period of 2.02$\pm$0.03…

We report on the detection and follow-up high cadence monitoring observations of MAXI J1659-152, a bright Galactic X-ray binary transient with a likely black-hole accretor, by Swift over a 27 day period after its initial outburst detection.…

We present the first optical photometry of the counterpart to the candidate intermediate polar RX J0153.3+7446. This reveals an optical pulse period of 2333s +/- 5s. Reanalysis of the previously published ROSAT X-ray data reveals that the…

We present near-infrared $J$ band photometric observations of the intermediate polar WX Pyx. The frequency analysis indicates the presence of a period at 1559.2 $\pm$ 0.2 seconds which is attributed to the spin period of the white dwarf.…

Optical and X-ray observations suggested that the 9.38 h binary, SWIFT J0746.3- 1608 could be a Cataclysmic Variable of the magnetic or nova-like type, or a low mass X-ray binary. Its optical, UV, and X-ray light curves are strongly…

We present a comprehensive broadband spectral and variability study of the newly detected black hole X-ray binary Swift~J1727.8--1613 in the intermediate states during its 2023 outburst, using multi-mission observations from NICER, NuSTAR,…

We report the results of long-term time series photometry on RX J2133.7+5107 (also known as 1RXS J213344.1+510725) obtained at several observatories. Using data taken during 17 years, we determined the current value of the spin period of…

SAX J0635.2+0533 is a binary pulsar with a very short pulsation period ($P$ = 33.8 ms) and a high long-term spin down ($\dot P$ $>$ 3.8$\times10^{-13}$ s s$^{-1}$), which suggests a rotation-powered (instead of an accretion-powered) nature…

We report on the first pointed X-ray observations with XMM-Newton and RXTE satellites of the X-ray source RXJ0757.0+6306=HT Cam. We detect a strong 515s X-ray modulation confirming the optical photometric period found in 1998, which…

We report the first time-resolved photometric and spectroscopic optical observations of the X-ray source RX J2133.7+5107, identified in the ROSAT survey. A clear persistent optical light pulsation is discovered with fast photometry at a…

We observed the intermediate polar RX J0558+53 with the 4.2m WHT and find in the pulsed emission lines, a ``corkscrew'' pattern, which indicates a two-pole white dwarf accretion. The ``corkscrew'' pattern consists of two emission-line…

We report the results from follow-up observations of two Roche-lobe filling hot subdwarf binaries with white dwarf companions predicted to have accretion disks. ZTF J213056.71+442046.5 (ZTF J2130) with a 39-minute period and ZTF…

The X-ray transient Swift J1727.8-1613 ended its 10-month discovery outburst on June of 2024, when it reached an optical brightness comparable to pre-discovery magnitudes. With the aim of performing a dynamical study, we launched an optical…

We present a detailed timing study of the pulse profile of Swift J0243.6+6124 with HXMT and Fermi/GBM data during its 2017 giant outburst. The double-peak profile at luminosity above $5\times10^{38}$erg\,s$^{-1}$ is found to be 0.25 phase…

We report the discovery of a new detached, double white dwarf system with an orbital period of 39.8 min. We targeted SDSS J163030.58+423305.8 (hereafter J1630) as part of our radial velocity program to search for companions around low-mass…

RX J1914.4+2456 and RX J0806.3+1527 have been proposed as double degenerate binaries with orbital periods of 569s and 321s respectively. An alternative model, in which the periods are related to the spin of a magnetic white dwarf in an…

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 both outburst and quiescence, which are thought to be the result of a high…