Surya Siddhanta
नतज्या +अक्षज्ययाभ्यस्ता त्रिज्याप्ता तस्य कार्मुकम्। वलनाम्शा सौम्ययाम्याः पूर्वापरकपालयोः॥
Find the zenith distance[1] (in the prime vertical of the body which is to be eclipsed), multiply its sine by the sine of the latitude of the place, and divide the product by the radius. Find the arc whose sine is equal to the quotient; the degrees contained in this are called the degrees of the (Áksha or the latitudinal) valana: they are north or south according as the body is in the eastern or western hemisphere of the place. [1.The distance of the circle of position (passing through the body) from the zenith of the place is called the zenith distance in the prime vertical of the body. The rough amount of this can be easily found by the following simple proportion. As half the length of the day of the body : 90. :: the time from noon of the body at a given time : the zenith distance in the prime vertical at the given time. B. D.]
english translation
natajyA +akSajyayAbhyastA trijyAptA tasya kArmukam। valanAmzA saumyayAmyAH pUrvAparakapAlayoH॥
hk transliteration by Sanscript