  HD 189733 b is one of the most well-studied exoplanets due to its large
transit depth and host star brightness. The focus on this object has produced a
number of high-cadence transit observations using high-resolution optical
spectrographs. Here we present an analysis of seven full H$\alpha$ transits of
HD 189733 b using HARPS on the 3.6 meter La Silla telescope and HIRES on Keck
I, taken over the course of nine years from 2006 to 2015. H$\alpha$
transmission signals are analyzed as a function of the stellar activity level,
as measured using the normalized core flux of the Ca II H and K lines. We find
strong variations in the strength of the H$\alpha$ transmission spectrum from
epoch to epoch. However, there is no clear trend between the Ca II core
emission and the strength of the in-transit H$\alpha$ signal, although the
transit showing the largest absorption value also occurs when the star is the
most active. We present simulations of the in-transit contrast effect and find
that the planet must consistently transit active latitudes with very strong
facular and plage emission regions in order to reproduce the observed line
strengths. We also investigate the measured velocity centroids with models of
planetary rotation and show that the small line profile velocities could be due
to large velocities in the upper atmosphere of the planet. Overall, we find it
more likely that the measured H$\alpha$ signals arise in the extended planetary
atmosphere, although a better understanding of active region emission for
active stars such as HD 189733 are needed.
