Apparently cosmic ray activity changes up to 15 days before, discussed here[1]. Two hours, while certainly useful, seems short. Days would surely be better. Of

Apparently cosmic ray activity changes up to 15 days before, discussed here[1]. Two hours, while certainly useful, seems short. Days would surely be better. Of course, no reason not to use both approaches. [1]: https://news.ycombinator.com/item?id=36358672 https://news.ycombinator.com/item?id=36358672