Ritual

Extant astronomical charts were used to ascertain the sun's
altitude and zenith distance and its declination; to find the
declination of a planet or star; to find the degree of azimuth of a
planet or star; to determine celestial latitudes and longitudes; to
calculate position during eclipse. For the same purposes, astronomical
observatories, or Yantras, were also built, at a
comparatively later date, by Jai Singh II (AD 1699-1744). Their
equipment included the mural quadrant, a meridional wall set in
the plane of the meridian, sloping up to point to the North Pole,
charts of the celestial sphere and a huge gnomon.
Astronomical findings greatly influence the whole gamut of
tantric ritual. All practices, including the preparations of
alchemical products, are preconditioned by time, planetary
positions and the observance of the calendar. Astronomy also laid
the theoretical foundation for the practical application of
astrology, the science of the influence of the stars on human and
terrestrial phenomena, which flourished in logical sequence to other
disciplines.
Astrology
Hindu astrology is predominantly an extension of astronomy, to
such an extent that many ancient treatises on astronomy
incorporate a section to astrology. The Surya-Siddhanta devotes
a chapter to astrology, but two major works, Brihad-jataka
and Laghu-jataka, which are ascribed to Varaha-Mihira, deal
Jaiprakdsh Yantra, the crest jewel
of all yantras. The sun's position
can be calculated by the shadow of
the intersecting wires on its concave
sides falling on its surface, Jaipur
observatory, Rajasthan, 1728.
Bronze.
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