Vedanga and Jyotish - Shiksha (Education), Kalpa, Vyakaran (Grammar), Nirukta, Chhand (verses) and Jyotish (astrology) come in Vedanga. From this it is clear that Jyotish (astrology) is a part of Vedanga.

The events of solar and lunar eclipses have been found to be justified by scientific and astrological calculations, from this it is clear that these are pure mathematical calculations, which have been correct/proper for centuries, then how to say that Jyotish (astrology) is not a mathematical science?

Jyotish (Astrology) has three wings - 1 - Mathematics principles, 2 - Samhita, 3 - Jataka.

Kundli Astrology: - This is the science based on Kundli. It has three parts - Siddhant Jyotish, Samhita Jyotish and Hora Shastra. According to this knowledge, the horoscope is made based on the planet, star or Nakshtra (constellation) where were in the sky at the time of person's birth.

Indian Month Name - In Indian tradition, it is said that when the month begins, due to the position of the Moon in the following Nakshtra (constellations), the names of the months fall from the Nakshtra (constellations): -

The lunar year is usually 11 days shorter than the solar year. Vikram Samvat dates back to 57 years before AD. Information about Indian festivals is available from Vikram Samvat itself.