From Ernst Pollmann , who is a major contributor on the study of several stars, P cygnii would be a good target for time resolved spectroscopy in h alpha.
Ernst citation: "
a really great considerations!
You are the first one under the amateurs (so far I know), who is willing
to perform such a kind of observation, in order to figure out more about short-term variations of this star.
(about Balmer's and He lines) Yes, you can expect a lot of variations in terms of line profile, RV, FWHM and EW. But you have to know, in most cases it's not so easy to understand the physical background.
So, that's one of the reasons, why we within the AAVSO long-term campaign are concentrating on the Halpha region.
This spectral area is fairly well understandable. And you have to know, there are often contemporaneous photometric Vmag and Bmag values at the AAVSO data base. "
With enough spectral resolution P cyg show fast variations specially in h alpha depending from clouds around this star. It is not an observationnal time consuming object, 15mn is enough to achieve a good snr at R 10000 to 15000, so let do time resolved spectrocopy to unveil star environment !