  We show the softest ever spectrum from Cyg~X-1, detected in 2013 with Suzaku.
This has the weakest high energy Compton tail ever seen from this object, so
should give the cleanest view of the underlying disk spectrum, and hence the
best determination of black hole spin from disk continuum fitting. Using the
standard model of a disk with simple non-thermal Comptonisation to produce the
weak high energy tail gives a high spin black hole. However, we get a
significantly better fit by including an additional, low temperature thermal
Comptonisation component, which allows a much lower black hole spin.
Corroboration of the existence of an additional Compton component comes from
the frequency dependent hard lags seen in the rapid variability in archival
high/soft state data. These can not be explained if the continuum is a single
non-thermal Comptonisation component, but are instead consistent with a
radially stratified, multi zone Comptonisation spectrum, where the spectrum is
softer further from the black hole. A complex multi-zone Comptonisation
continuum is required to explain both spectra and timing together, and this has
an impact on the derived black hole spin.
