Brihat Samhita of Varahamihira

BRIHAT SAMHITA. [Ch. 2.
4

divisions of time and also of divisions of space.

He must have a clear knowledge of the causes of Solar, Savana civil day based on sunrises, Siderial, and Lunar months as well as of intercalary lunations and intercalary days.

He must have a knowledge of the beginning and end of Shashtyabda a cycle of 60 years, a yuga 5 years, Varsha a year, Masa a month, Thina a day, and hora an hour and of their lords.

He must know the solar and other divisions of time, their similarity and dissimilarity, and must be capable of propounding the fitness or unfitness of each for particular purposes: these divisions of time are, of Man, of Devas gods, of Jupiter, of Pithris ancestral spirits, of Star (Siderial), of the Sun (solar), of the Moon (lunar), of the Earth (terrestrial), and of Brahma.

If the methods of calculation given in the five Astronomical works mentioned above should produce different results, he must be able to calculate correctly the places of the sun and planets by actual observation (by means of shadow and water level and with the help of Astronomical instruments) of the termination of their ayana northward and southward course, of their being due east to the observer after rising, and of their altitude at any time.

He must know the reason for the correction required for the conversion of the heliocentric into geocentric longitude and vice versa; the causes of the ayana of the sun and planets and of their slow and rapid movements at different times.

In solar and lunar eclipses, he must be able to calculate the times of the commencement and end of the eclipses, the places of first and last contact, the magnitude and duration of the eclipse; in total eclipses, he must be able to calculate the time between middle eclipse and the beginning or end of total phase (this period being technically known as Vimarda). He must also know the color of the eclipsed lunar disc. He must be able to calculate beforehand the times of the Moon's conjunction with the planets as well as of planetary conjunctions.

30 times the interval from sunrise to sunrise. See verses 23 and 24, Chapter VIII.