Surya Siddhanta
इष्टाग्राघ्नी तु लम्बज्या स्वकर्णाङ्गुलभाजिता । क्रान्तिज्या सा त्रिजीवाघ्नी परमापक्रमोद्धृता॥
The quotient, (thus found), is the sine of the Sun's declination; multiply it by the radius and divide the product by the sine of the greatest declination; find the arc in signs, degrees, &c.; from this arc and that quarter of the ecliptic in which the Sun is situated at the given time the Sun's longitude can be determined (as mentioned before in Ślokas 18 and 19 of this Chapter).
english translation
iSTAgrAghnI tu lambajyA svakarNAGgulabhAjitA । krAntijyA sA trijIvAghnI paramApakramoddhRtA॥
hk transliteration by Sanscript