Astronomical Observation Dating

Astronomical observation dating is the way this atlas records holidays that are not reckoned by any calendar system at all but are set directly by the sky, for example by a solstice, an equinox or a sighting of the moon. Wikipedia defines a calendar as a system of organizing days, giving names to periods of time such as days, weeks, months and years; the holidays gathered here are the ones that skip that system and are fixed by observation of the heavens instead. It is recorded as its own calendar entity so that the holidays and festivals reckoned by it can be grouped and compared in one place, while each holiday entry keeps its own dating facts and sources.