The Ujjain Observatory, also known as the Vedhshala, is believed to be the oldest astronomical observatory in India, dating back to the 5th century BCE.

Varahamihira was a renowned astronomer and mathematician who lived in the 6th century CE and is associated with the Ujjain Observatory. He made significant contributions to astronomy, including the development of the Pancha Siddhantika, a treatise on astronomy and astrology.

The early Indian observatories were primarily used for observing celestial events, such as the movement of the sun, moon, and stars, and for studying their patterns and relationships.

The gnomon, a simple instrument consisting of a vertical rod or pillar, was widely used in early Indian observatories for measuring the altitude of celestial bodies and determining the time of day.

The Jantar Mantar observatories were primarily designed for compiling astronomical tables, which were used for various purposes, including predicting the positions of celestial bodies, calculating eclipses, and determining the time of day.

The Konark Sun Temple was built in accordance with the principles of Vastu Shastra, an ancient Indian architectural system that considers the alignment of buildings with celestial bodies.

The Nalanda University observatory was known for conducting observations of stellar occultations, which occur when a star is hidden behind the moon or a planet.

Aryabhata, a renowned astronomer and mathematician, proposed the theory of elliptical orbits for planets, challenging the prevailing belief of circular orbits.

The Samrat Yantra was primarily used for measuring the altitude of celestial bodies, such as the sun, moon, and stars, with high precision.

The Fatehpur Sikri Observatory was constructed during the reign of the Mughal emperor Akbar and was known for its advanced instruments and observations.

The Jai Prakash Yantra was designed for calculating the positions of planets and other celestial bodies based on their orbital parameters.

Aryabhata was the first Indian astronomer to propose the heliocentric model of the solar system, where the sun is at the center and the planets revolve around it.

The Mishra Yantra was specifically designed for observing solar eclipses and studying their duration and magnitude.

Aryabhata is credited with developing the concept of zero and introducing it into mathematics, which had a profound impact on the field.