To caste a horoscope, following accurate details are required:
Date of birth
Time of Birth: It is recorded for India as IST - Indian Standard Time (and for other countries as GMT - Greenwich Mean Time). GMT is 5½ hours ahead of IST. But for casting a horoscope, Local Mean Time is used, which depends on the place of birth.
Place of Birth: Logitude and latitude of the place of birth are used to find the time correction to be applied to the IST, to find out the Local Mean Time.
Longitude: It is the arc drawn from North Pole to South Pole to mark the location in degrees of a particular place from a central place (Greenwich). All places are located either to the West or to the East of Greenwich. For example, the longitude of Bombay is 72° 50' E.
Latitude: It is the arc drawn to mark the location in degrees of a particular place North or South of Equator. For example, the latitude of Bombay is 18° 58' N.
Sidereal Time: It is the time taken by the earth to make one full rotation. It is not exactly 24 hours, but goes on changing according to increase or decrease in the duration of days and nights. It is called Vernal Equinox time and it is a measure of earth's rotation with respect to the equinox, which has a very small retrograde motion. Sidereal time is used for calculation of the Ascendant as explained below:
Calculation of Ascendant
Calculation of Longitudes of Planets
Calculation of Houses(Bhava)
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