Warning: SIS Gain Problem

[Koji Mukai <mukai@milkyway.gsfc.nasa.gov>]

We have discovered a significant problem in the gain calibration of SIS data,
particularly for SIS-1 data taken during AO-8 (calendar 2000). It appears that
the Charge Transfer Inefficiency (CTI) is evolving non-linearly with time,
whereas we currently use linear extrapolations from the last determination of
CTI values on 1997 March 11. 

Please consult the preliminary report we have posted at:

	http://heasarc.gsfc.nasa.gov/docs/asca/cti_nonlinear.html

for further details.