This is an translation of a thousand plus year old Hindu textbook on astronomical calculations (originally written in Sanskrit). The English translation is included (verse by verse) along with extensive notes and explanations by the translator. The text gives prescriptions on Hindu calendar calculations (including the rather complicated Hindu lunar calendar), calculating the celestial coordinates of the Sun, Moon and visible planets, along with the ascending and descending node of the Moon, and calculations of the circumstances of solar and lunar eclipses. A prescription is given for creating a sine function table (a Hindu invention) to be used with the astronomical calculations.

This old textbook is not for the mathematically faint of heart. Even the translators extensive notes are difficult in places to wade through. If you have some ability in algebra, trigonometry and geometry and you are persistent you can, however, follow the calculations with the help of the translators notes. Many of the calculations are in base 60 arithmetic (much like our modern hour and minutes of time notations). In places the text and notes are a little difficult to follow. However, there are worked-out-examples of the calculations to help your understanding. I worked through all the calculations for the predictions of a solar eclipse, and, in all but a few places, exactly reproduced the examples given by the translator of the text. The results were quite accurate predictions of the times for solar eclipses. The predictions were most accurate for tenth century eclipses as that is the approximate date of the data provided in the text.

This is a fascinating book if you are interested in ancient astronomical calculations. The Hindu prescriptions appear to be a somewhat modified versions of the calculations prescribed by the second century Greek astronomer Ptolemy in his book the Almagest.