This page tests some of the functions and algorithms the site relies on. In most cases, you should see only tiny differences between the reference values and the values calculated by airmass.org. The ratio column is highlighted in green for quantities that are accurate to better than one part in a million, yellow for better than one part in a thousand and orange for worse than one part in a thousand. For the purposes of testing, the results of
getLunarSigmas() shown here use all the coefficients listed in Meeus, while in the actual observability calculations, smaller periodic terms are dropped. The accuracy in practice is about 1 per cent.
airmass.org version number:
Results from airmass.org are compared to results from PHP
date_sun_info() for four locations (London, Auckland, Los Angeles and Tromsø) on today's date (2021-07-31), and 2021-01-01.