[Ernest_at_the_Beach]

Thanks.

Trying to do some web research....came across this very nice paper.

And now know what the H & K project was at Mt Wilson....here in Los Angeles.

Will look for something that lays it out nicely....although this paper does a nice summary.

[Ernest_at_the_Beach]

Dropping this link here with a brief into :

The Solar-Stellar Spectrograph

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Ca II H&K stellar time series

At last the rubber meets the road! We have described in gruesome detail how we extract the spectra from the raw CCD frames, and how we place the Ca II H&K spectra on an absolute intensity scale. In this article, we describe (in technical terms) how we produce the time series plots of activity in the various stars on our program. The data products of this step are some of the fundamental results that come from our program, revealing the long-term activity changes in the Sun and Sun-like stars.

[Marine_Uncle]

Thanks Ernest.