  We have analysed four ASCA observations (1994--1995, 1996--1997) and three
XMM-Newton observations (2005) of this source, in all of which the source is in
high/soft state. We modeled the continuum spectra with relativistic disk model
kerrbb, estimated the spin of the central black hole, and constrained the
spectral hardening factor f_col and the distance. If kerrbb model applies, for
normally used value of f_col, the distance cannot be very small, and f_col
changes with observations.
