The Universal System of Astronomy, Part Two

Siddhānta [Siddhāñjana] 3 Then, from the maximum sine of declination parama-krāntijyā; the sine of the maximum angle (approx. 24°) between the ecliptic and the equator, which is compared to the radius trijyā; the standard radius used in Indian trigonometry, often 3438 minutes, if the base is equal to the sine of declination, then what is the value of the declination? From that, the arc dhanu; literally "a bow," referring to the arc-length derived from a sine value is determined.

If the Sun is in the first quadrant 0° to 90° from the vernal equinox, the calculated arc itself is the Sun’s position. In the second quadrant 90° to 180°, the arc should be subtracted from the half-circle 180° to find the Sun’s longitude. In the third quadrant 180° to 270°, one should add the arc to the half-circle 180°. In the fourth quadrant 270° to 360°, the arc should be subtracted from the full circle 360°.

From this, the corrected Sun is revealed. When this value is adjusted by the precession of the equinoxes ayanāṃśa; the longitudinal difference between the tropical and sidereal zodiacs, the True Sun original: spashta-surya is established.

By reversing this process, starting from the Aries Mesha point, the position becomes clear. This calculation varies depending on the specific location original: pratideśa-jāni-bhinnā; acknowledging that astronomical observations change based on the observer's latitude. The precessional correction is applied to the signs starting from Aries. These are associated with the six seasons original: ṣaḍ-ṛtavaḥ. Rama [Scribe/Author]

The relationship between the signs of the ecliptic krāntivṛtta; the Sun's apparent path and the seasons of the solar year is as follows:

Therefore, the year is divided by the transit of the Sun through these signs. In the spring, when the Sun occupies Aries and Taurus, the months are known as Chaitra and Vaishakha...