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   PR # 42027
   RX J0558.0+5353 belongs to the intermediate polar (IP) subclass of
   magnetic cataclysmic variables, several members of which have been
   observed with ASCA. What distinguishes this IP from others is that
   (1) it has a distinct soft X-ray component; and (2) optical and soft
   X-ray emissions from this IP are modulated twice per 545.45 s spin
   period. We propose the first hard X-ray observation of this IP. We
   will compare the spin pulse profiles at different energies, and
   perform phase-resolved spectroscopy. Such studies are essential to
   evaluate the energy budget (soft to hard X-ray luminosity ratio) of
   this system and to understand the origin of the twice per spin
   pulsation in soft X-rays. will also study emission line intensity
   ratios to infer the white dwarf mass.
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