Jyotihshastra: Astral and Mathematical Literature c4.20

c4.20

Lagadha has retained the Vedic list of twenty-seven nakṣatras beginning with Kṛttikā, but treats them not as constellations, but as measurements of arcs on the ecliptic of 13;20° each beginning with the vernal equinox. This adaptation means, of course, that the actual position of the equinoctial and solsticial colures with respect to the fixed stars can not be used for dating the JV. He introduced into Indian astronomy the Mesopotamian concepts of the possibility of describing mathematically the periodicity of celestial motions; their use of linear zig-zag functions to describe periodic deviations from the mean (Ṛk 7 = Yajus 8 and Ṛk 22 = Yajus 40); and their artificial time-unit, a thirtieth of a mean synodic month (named tithi in Sanskrit). He gives rules for computing the mean longitudes of the Sun and the Moon in terms or nakṣatras, but mentions neither the planets nor the zodiacal signs. Other texts that reflect this level of astronomy are Kauṭilya’s Arthaśāstra (2, 20) and the Buddhist Śārdūlakarṇāvadāna (Divyāvadāna 33). The revised system of the Yajus recension is used in the Jaina Sūriyapannatti and Caṃḍapannatti and in the verses ascribed to Garga in Somākara’s Bhāṣya.