Contact

One address, read by a person. There is no form, because a form would need a database and this site does not have one.

Corrections are the ones that get answered first

If a number here disagrees with a source you trust, the source is probably right and I want to know. Please include the city and the figure you are looking at — the URL is enough. The methodology page lists every source and every approximation, and is the fastest way to see whether a discrepancy is a bug or a stated limitation.

What cannot be answered

Anything personal or medical. This is a solar geometry calculator, not a clinician, and a figure on this site is a clear-sky upper bound rather than a recommendation for you. Talk to a doctor about vitamin D.