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   PR # 21017
     We propose to observe the Wolf-Rayet binary Gamma Vel (WC8 + O9I) at
    two different orbital phases - once near apastron when the Wolf-Rayet
    star is in front of the O supergiant and again near periastron when  
    it is behind. These observations will test the theory that the X-rays
    originate in a colliding wind shock between the two stars, and will  
    provide information on wind elemental abundances that can  be used to
    constrain evolutionary models.                                       
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