Indian Astronomer Varah-mihir.

Varahamihira.(505-587)

Varahamihira's knowledge of astronomy was thorough. His monumental work progresses through astronomy and culminates in two treatises on astronomy, showing calculations based on reckoning and even giving complete mathematical charts and tables. Although Varahamihira's writings give a comprehensive picture of 6th-century India, his real interest lay in astronomy and astrology. He repeatedly emphasized the importance of astrology and wrote many treatises on shakuna as well as the Brhaj-Jataka, Great Birth and the Laghu-Jataka, Short Birth, two well-known works on the casting of horoscope.
He worked at Ujjain which had been an important center for mathematics since around 400 AD. The school of mathematics at Ujjain was increased in importance due to Varahamihira working there and it continued for a long period to be one of the two leading mathematical centers in India, in particular having Brahmgupta as its next major figure.
The most famous work by Varahamihira is the Panch Siddhant dated 575 AD. This work is important in itself and also in giving us information about older Indian texts which are now lost. The work is a treatise on mathematical astronomy and it summarises five earlier astronomical treatises, namely the sun,romaka Paulisa, Vasistha and Paitamaha siddhantas.
The Pancasiddhantika of Varahamihira is one of the most important sources for the history of Hindu astronomy before the time of Aryabhatta.
One treatise which Varahamihira summarises was the Romaka-Siddhanta which itself was based on the epicycle theory of the motions of the Sun and the Moon given by the Greeks in the 1st century AD. The Romaka-Siddhanta was based on the tropical year of Hipparchus and on the Metonic cycle of 19 years. Other works which Varahamihira summaries are also based on the Greek epicycle theory of the motions of the heavenly bodies. He revised the calendar by updating these earlier works to take into account precession since they were written. The Pancasiddhantika also contains many examples of the use of a place-value number system.
There is, however, quite a debate about interpreting data from Varahamihira's astronomical texts and from other similar works. Some believe that the astronomical theories are Babylonian in origin, while others argue that the Indians refined the Babylonian models by making observations of their own. Much needs to be done in this area to clarify some of these interesting theories.
Varahamihira was one of the most famous astronomers in Indian history. His work Brihatsamhita contains
description of heavenly bodies, their movements and conjunctions, meteorological phenomena, indications of the omens these movements, conjunctions and phenomena represent, what action to take and operations to accomplish, sign to look for in humans, animals, precious stones, etc.