Cool Moon Facts by Whip

Real astronomy and dated history, with sources. Documented traditions and folklore. Modern lunar astrology · symbolic, not predictive.

Chart basics · Houses · Advanced

Sidereal time

Also called local sidereal time, ARMC, LST, RAMC

Time kept by the stars rather than the Sun; at a place, it says which part of the sky is on the meridian.

A sidereal day is about four minutes shorter than a solar day. Local sidereal time, expressed as an angle (the right ascension of the Midheaven, RAMC or ARMC), is the key number for houses: it fixes the Midheaven and, with the latitude, the Ascendant.

How it is worked out
This site uses Greenwich apparent sidereal time plus the east longitude.
  • Kind: Astronomy, Calculation
  • Tradition: Astronomy
  • In this site’s birth chart: used

Related: Midheaven, Ascendant, House system, Delta T

Written for Cool Moon Facts in its own words. An astrology source documents what astrologers believe or practise; it does not establish that astrology works.

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