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   52015
   ROSAT HRI soft X-ray observations of the O7 V star Theta-1 Ori C have
   confirmed the 15.4 day rotational period first discovered from H-alpha
   and He II observations. This periodicity has also been detected in IUE
   observations of CIV absorption. These data suggest that Theta-1 Ori C
   is an oblique magnetic rotator, and, hence, may be the only known
   magnetic O-star. We propose to observe the Trapezium at Theta-1 Ori C's
   rotational phases 0.0 and 0.5 in order to determine the origin of its
   X-ray emission. These data will allow us to distinguish between a
   varying wind-absorption model and a model where the active-region is
   eclipsed by the star itself.
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