Surya Siddhanta
ऊने भूवृत्तपादे तु द्विज्यापक्रमयोजनैः। धनुर् मृगस्थः सविता देवभागे न दृश्यते॥
Subtract from a quarter of the earth's circumference the number of yojanas derived from the declination iound by the sine of two signs : at that distance from the equator the sun is not seen, in the hemisphere of the gods, when in Sagittarius and Capricorn ; . -
english translation