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   61123
   The powerful radio galaxy 3C109 is the most luminous object (2e45 erg/s
   in the 2-10 keV band) known to show a broad iron line. Radio jets are
   seen in the object down to parsec scales, so a determination of the
   iron line profile will illuminate our understanding of the interaction
   between disks and jets. Disk accretion appears to be necessary for the
   formation of jets but the mechanism is highly uncertain. X-ray
   observations offer the only means to determine disk properties on the
   relevant inner scale. The previous 36 ks ASCA observation (Allen et al
   1997) showed that the inner radius of the disk must be less than 70 Rs;
   the 100 ks observation proposed here will bring that limit to less than
   30 Rs, considerably less if the source is as bright as when observed by
   ROSAT in 1991.
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