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   71126
   Time variations in intensity and profile of an iron K-emission line,
   observed in Seyfert galaxies with ASCA, provide crucial information on
   the emission region and the cause of the time variations. To obtain
   these information, we propose long-look observation of a typical
   Seyfert galaxy NGC 5506, which exhibits rapid time variations and a
   broad iron line profile in the energy spectrum. We will compare
   observed time variations of the iron line with variations expected from
   some theoretical models explaining the cause of the time variations,
   and test the validity of the interpretation on the observed broad iron
   line profiles with the relativistic effect.
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