UW CrB ( MS1603+2600 ) is a peculiar short period X-ray binary that exhibits extraordinary optical behaviour .
The optical light curve shape of the system changes drastically from night to night , without any changes in overall brightness .
Here we report X-ray observations of UW CrB obtained with XMM-Newton .
We find evidence for several X-ray bursts confirming a neutron star primary .
This considerably strengthens the case that UW CrB is an Accretion Disc Corona ( ADC ) system located at a distance of at least 5–7 kpc , ( 3–5 kpc above the galactic plane ) .
The X-ray and optical monitor ( UV+optical ) light curves show remarkable shape variation from one observing run to another , which we suggest are due to large scale variations in the accretion disc shape resulting from a warp which periodically obscures the optical and soft X-ray emission .
This is also supported by the changes in phase-resolved X-ray spectra .