  We report the discovery of the cessation of flickering in dips in the black
hole candidate Cygnus X-1, detected for the first time in the ASCA observation
of May 9th., 1995. During this observation, particularly deep dipping took
place resulting in strong changes in hardness ratio corresponding to absorption
of the power law spectral component. The deadtime corrected light curve with
high time resolution clearly shows a dramatic decrease in the extent of
flickering in the band 0.7 - 4.0 keV during dipping, but in the band 4.0 - 10.0
keV, there is relatively little change. We show that the rms flickering
amplitude in the band 0.7 - 4.0 keV is proportional to the X-ray intensity in
this band which changes by a factor of almost three. This is direct evidence
that the strong Low State flickering is intrinsic to the power law emission; ie
takes place as part of the emission process. The rms amplitude is proportional
to the intensity in the low energy band, except for a possible deviation from
linearity at the lower intensities. If confirmed, this non-linearity could
imply a process such as electron scattering of radiation which will tend to
smear out the fluctuations, or a process of fluctuation generation which
depends on radial position in the source. Thus timing observations during
absorption dips can give information about the source region and may place
constraints on its size.
