The Jewel of Auspicious Moments

The Great Birth, The Collection of Essence, The Method of Natal Astrology, The Jewel of Natal Astrology, and The Rosary of Natal Astrology are some of the famous Horā texts Horā refers to predictive astrology focusing on individual birth charts. Among natal texts, the "Great Birth" (Brihat Jataka) by the teacher Varahamihira holds a position of great importance.

Siddhānta (Mathematical Astronomy)

In this branch of Siddhānta, the positions of the planets and stars in the sky, the specific movements of the planets, planetary orbits, the method of calculating elapsed days original: ahargana-anayana-krama; the calculation of the number of days passed since a fixed epoch, the procedure for clarifying planetary positions original: graha-spashtikarana; calculating the true longitude of planets from their mean positions, and the consideration of solar and lunar eclipses are described. Similarly, the determination of direction, place, and time, the nine different systems of time measurement such as Solar, Civil (Savana), Lunar, etc., trigonometric calculations specifically the calculation of sines (jya), and corrections for terrestrial latitude and longitude are also subjects of study in this branch.

A text where the clarification of planets is performed by calculating the elapsed days from the beginning of the Kalpa a vast cosmic cycle of 4.32 billion years is called a Siddhānta. Where the elapsed days are brought from the beginning of a Yuga an age or epoch, it is called a Tantra. And where the elapsed days and planetary operations are calculated starting from a chosen epoch year, that is called a Karana a practical astronomical handbook. Furthermore, it is divided into three parts: Arithmetic, Algebra, and Geometry. In very ancient times, Indian mathematicians conducted research with great effort in the field of mathematics and established many principles. The decimal system discovered by ancient Indian astronomers is accepted even by modern scholars. The principle of the Earth's force of attraction (gravity), which has been presented by modern scientists, is seen clearly established by Bhaskaracharya in the text The Crest-Jewel of Siddhāntas. As it is said:

This Earth possesses an attractive power; by that power, she pulls any heavy object in the sky toward herself. That object appears to be falling, but in space, where could it fall? It is being pulled from all sides equally.

Aryabhata's Aryabhatiya, Lalla's Increaser of Intelligence, Brahmagupta's The Correct Siddhānta of Brahma, and Bhaskaracharya's The Crest-Jewel of Siddhāntas are famous Siddhānta texts.

Samhitā (Mundane Astrology)

In this branch of Samhitā, the auspicious and inauspicious results concerning the nation are determined, rather than those of an individual. The good and bad effects on the world caused by the movement of the Sun and other planets through the circle of constellations...