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The local hour angle (LHA) of an object in the observer's sky is = or = + where LHA object is the local hour angle of the object, LST is the local sidereal time, is the object's right ascension, GST is Greenwich sidereal time and is the observer's longitude (positive east from the prime meridian). [3]
Sidereal time vs solar time. Above left: a distant star (the small orange star) and the Sun are at culmination, on the local meridian m. Centre: only the distant star is at culmination (a mean sidereal day). Right: a few minutes later the Sun is on the local meridian again. A solar day is complete.
Right ascension is measured eastward up to 24 h along the celestial equator from the primary direction. Right ascension (abbreviated RA; symbol α) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the Earth. [1]
Right ascension is usually measured in sidereal hours, minutes and seconds instead of degrees, a result of the method of measuring right ascensions by timing the passage of objects across the meridian as the Earth rotates. There are 360° / 24 h = 15° in one hour of right ascension, and 24 h of right ascension around the entire ...
Sidereal time is the hour angle of the equinox. However, there are two types: if the mean equinox is used (that which only includes precession), it is called mean sidereal time; if the true equinox is used (the actual location of the equinox at a given instant), it is called apparent sidereal time.
An object's right ascension and the local sidereal time can be used to determine the time of its culmination (see hour angle). The term meridian comes from the Latin meridies, which means both "midday" and "south", as the celestial equator appears to tilt southward from the Northern Hemisphere.
Sidereal astrology is not necessarily a lesser-known form of astrology, but the reason this might be your first time hearing about it is simply because it is lesser known in the West.
The "width" of the figure is due to the equation of time, and its angular extent is the difference between the greatest positive and negative deviations of local solar time from local mean time when this time-difference is related to angle at the rate of 15° per hour, i.e., 360° in 24 h. This width of the analemma is approximately 7.7°, so ...