Ancient Luni-Solar and Planetary Ephemerides

This web page is organized as follows:

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The observatory of Alexandria with an astronomer measuring the heavens with some instruments (cross staff, mariner's astrolabe) which actually belong to a much later period (source: Camille Flammarion, Astronomie Populaire: Description générale du ciel, Paris: 1880).
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This website provides JavaScript modules for generating luni-solar and planetary ephemerides based on historically important astronomical tables commonly employed by Near Eastern, Hellenistic, Islamic and Western astronomers and astrologers from the beginning of our era to the 17th century.

The web versions of these tables contain modules for date conversions between the particular calendar systems adopted in the original tables and the commonly used Julian or Gregorian calendars. Other modules give the geocentric positions of the Sun, the Moon and the planets for a given date and specify the various auxiliary angles and other quantities that had to be computed to obtain these positions. Also included are a number of modules which tabulate various astrological aspects and several other horoscopic quantities.

These JavaScript modules are designed to supplement the astronomical tables of Neugebauer (1912-’25, 1929), Schoch (1927), Tuckerman (1962, 1964), Stahlman & Gingerich (1963), Goldstine (1973), Hunger & Dvorak (1981), Gingerich & Welther (1983), Houlden & Stephenson (1986) and others, which are based on modern astronomical theories of the luni-solar and planetary motions and which have been widely used in the past century to date and verify ancient astronomical records.

However, for many ancient astronomical records the above-mentioned tables may give misleading results as the luni-solar and planetary positions mentioned in these records were often not derived from celestial observations but from calculations based on the astronomical tables that were then current. The differences between the modern and the ancient tables can easily amount to several degrees of arc and for the planet Mercury they can even range up to ten degrees of arc or more.

JavaScript Ephemerides of Historical Astronomical Tables

JavaScript ephemerides are currently available for the following astronomical tables:

Bibliography (chronological)

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