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   PR #    27
   Cyg OB2 includes 5 Einstein-IPC sources spreading on a 15-arcmin
   square, and is located within 25 arcmin of a bright X ray source, Cyg
   X 3. The obsreved data of Cyg OB2 provides a good exercise for dealing
   with a multiple source image. The scientific goal of this observation
   is investigation of the plasma characteristics around the OB stars.
   The excellent spectra obtained with SIS may show some emission lines
   from Oxygen. The time variation with time scale of several hundred
   seconds will be also expected and it provides the plasma size.
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