सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

230 However, here. there is one complication if we consider the तात्कालिकार्क ie. s the Sun at the given time. This position of s cannot be had unless we know the time, which is itself required. So we get in the first place the time pertaining to S'L, which is the time measured in sidereal units the position S' being that of the Sun at Sun- rise. If we don't take recourse to convert this time in sidereal units to Sāvana units using the proportion between them, then the alternative is to obtain the position S using the time obtained and then calculate the time again in Sāvana units. If the time given to find the Lagna, be sidereal, it goes without saying that we find it from S'. Also S' being given and if the time after sun-rise is required in sidereal units for a given Lagna, the method of succes- sive approximation is unnecessary. Verse 7. To find the Lagna before Sun-rise called Vilōmalagna. Suppose it be required to find the lagna before Sun- rise, given the time before Sun-rise. Obtain the then posi- tion of the Sun and find his Bhuktāsus; subtract them from the given time; from the remainder, subtract the rising times of as many Rāsis as could be, rāsis behind the Sun's position. If R be the remainder in the time after these subtractions, then R × 30/T where T is the rising time of is the next preceding Rāśi, together with n × 30, where n the number of integral Rāśis subtracted and the arc of the next Rāśi by which the Sun has advanced in his Rāśi at the time of the Lagna (known from the position of S found) the sum total of these three items being subtracted from the position of S gives the longitude of L. Comm. Easy. Verse 8. To obtain the East-West line.