The gavam ayana ritual in SB 4.6.2. is based on the motion of the sun [REF].
In the Maitrayana Brahmana Upanishad (6.14), the year is said to be into two portions, with the part from Magha to half of Śraviṣṭha associated with Agni, and the part from Sārpa to half of Śraviṣṭha associated with Varuna and Saumya (the moon).