The Astronomical Observatories of Jai Singh c15.s1.t2.3

c15.s1.t2.3

The five-year cycle appears to have commenced with the winter solstice, and Śraviṣṭha is said to have marked the beginning of this cycle, and also the beginning of the sun's progress, and also the winter solstice—all of which are in agreement. If Śraviṣṭha is to be identified with β, α, γ and δ Delphini (as it usually is), then it marked the winter solstice about B.C. 1100. But a list of asterisms given in the text begins with Aśvini (β, and γ Arietis), which marked the vernal equinox about the beginning of the Christian era. The Vedāṅga states that, during the northern progress of the sun, the days increase in length at an even rate of 1·57 minutes a day, or 4 hours 48 minutes in six months of 183 days²: the northern and southern progress are considered equal.