Bharatiya Jyotihshastra (History of Indian Astronomy), translated by R. V. Vaidya v1.c6.s2.7

v1.c6.s2.7

The history of mathematical astronomy in this part has been presented in the order of adhikāra or chapters, as already mentioned, viz., the mean motions, true motions, etc. A description of the celestial sphere, the system of observation, the precession of solstices, etc., have been given in the same part. In the treatment of these subjects references to several works and authors are required to be quoted, and without their knowledge some difficulty is likely to be experienced in rightly appreciating the discussion. Hence a detailed history of astronomical works and their authors is given in the chapter on the mean motions of planets in the beginning of ‘Part Two’ and a discussion of the mean places and motions of planets will be found in the same chapter. The chapter on the ‘true motions’ is devoted to the study of true positions, motions of planets and a detailed description of the five parts of the Pañcāṅga (almanac) and that of different Pañcāṅgas current in different provinces of our country.