2XMMi J225036.9+573154 - a new eclipsing AM Her binary discovered using
  XMM-Newton
  We report the discovery of an eclipsing polar, 2XMMi J225036.9+573154, using
XMM-Newton. It was discovered by searching the light curves in the 2XMMi
catalogue for objects showing X-ray variability. Its X-ray light curve shows a
total eclipse of the white dwarf by the secondary star every 174 mins. An
extended pre-eclipse absorption dip is observed in soft X-rays at phi=0.8-0.9,
with evidence for a further dip in the soft X-ray light curve at phi~0.4.
Further, X-rays are seen from all orbital phases (apart from the eclipse) which
makes it unusual amongst eclipsing polars. We have identified the optical
counterpart, which is faint (r=21), and shows a deep eclipse (>3.5 mag in white
light). Its X-ray spectrum does not show a distinct soft X-ray component which
is seen in many, but not all, polars. Its optical spectrum shows Halpha in
emission for a fraction of the orbital period.
