We present fast timing photometric observations of the intermediate polar V2069 Cygni ( RX J2123.7+4217 ) using the Optical Timing Analyzer ( OPTIMA ) at the 1.3 m telescope of Skinakas Observatory .
The optical ( 450-950 nm ) light curve of V2069 Cygni was measured with sub-second resolution for the first time during July 2009 and revealed a double-peaked pulsation with a period of 743.38 \pm 0.25 .
A similar double-peaked modulation was found in the simultaneous Swift satellite observations .
We suggest that this period represents the spin of the white dwarf accretor .
Moreover , we present the results from a detailed analysis of the XMM–Newton observation that also shows a double-peaked modulation , however shifted in phase , with 742.35 \pm 0.23 s period .
The X-ray spectra obtained from the XMM–Newton EPIC ( European Photon Imaging Camera ) instruments were modelled by a plasma emission and a soft black body component with a partial covering photo-electric absorption model with covering fraction of 0.65 .
An additional Gaussian emission line at 6.385 keV with an equivalent width of 243 eV is required to account for fluorescent emission from neutral iron .
The iron fluorescence ( \sim 6.4 keV ) and FeXXVI lines ( \sim 6.95 keV ) are clearly resolved in the EPIC spectra .
In the P _ { orb } –P _ { spin } diagram of IPs , V2069 Cyg shows a low spin to orbit ratio of \sim 0.0276 in comparison with \sim 0.1 for other intermediate polars .