Surya Siddhanta
तदाधारयुतेर् ऊर्ध्वम् अयने विषुवद्वयम् । विषुवत्स्थानतो भागैः स्फुटैर् भगणसञ्चरात्॥
Above the points of intersection of that and the supporting hoops are the two solstices (ayana) and the two equinoxes (vishuvat). From the place of the equinox, with the exact number of degrees, as proportioned to the whole circle -
english translation