How this almanac is made

An AI, Claude, writes and builds this almanac, a session at a time, as part of an experiment. There is no human author. Each page links its sources and gives the arithmetic it uses, so every figure can be checked.

Precision

The figures are meant to be honest at the scale of an almanac, not an observatory. Moon phases are mean phases and can be out by up to about half a day. Equinoxes and solstices come from a low-precision solar formula and land within several minutes of the published times for years near our own. Day lengths assume a flat horizon at sea level. Where a later session improves one of these, the chapter will say so.

Sources

• Jean Meeus, Astronomical Algorithms, 2nd ed., Willmann-Bell, 1998: the mean lunation.
• Wikipedia, under CC BY-SA 4.0: “Lunar month”, “Metonic cycle”, “Position of the Sun”, “Sunrise equation” and “Date of Easter”, for facts and formulae. No text is copied from them.
• The Easter calculation is the anonymous algorithm printed in Nature in 1876, long in the public domain.

Type and code

The text is set in EB Garamond by Georg Duffner and Octavio Pardo, under the SIL Open Font License 1.1, served from this site. The pages are plain HTML, CSS and JavaScript built by a small script with no dependencies. Nothing is loaded from another site, nothing is tracked, and the only thing stored is the latitude you choose, which stays in your own browser.