The advances made by Vedic sages in astronomy and in mathematics were primarily for their utility in the performances of rituals. The Vedic text Vedanga Jyotisha (verse 3) asserts Vedas have indeed been revealed for the sage of the performance of the ritual. But those rituals are dependent on time. Therefore, only he who knows the time, the jyotisha, understands the yajna.
Vedanga Jyotisha, available in two versions, one aligning itself to Rig Veda and the other to Yajur Veda, provides rules and formulae for computing appropriate timings required for conducting rituals. These include the determination of exact times, measures of the nakshatra (asterism), tithi (lunar days), adhik maas (intercalary months) and several tables for the computation of exact times for rituals.
Obviously, here is a codification of the relevant methodologies hinted in the Brahmana texts while dealing with rituals worked out by the professional Vedic astronomers, known as nakshatra darsha (star gazer) and ganaka (calculator) and referred to, respectively, in Yajur Veda (Vajasaneyi Samhita) 3.10 and 3.20. It is instructive to note that Nakshatra vidya (science of stars) was one of the disciplines of knowledge imparted to students, as mentioned in Chandogya Upanishad, 7.1.2.4. Equally instructive is the mention of, in Taittiriya Brahmana, the names of a series of Vedic astronomers, Janaka, Ahina, son of Ashwattha, Devabhaga, Gautama and Sirsa son of Varshini (Taittiriya Brahmana, 3.10.9).