The Universal System of Astronomy, Part Two

Investigation into the Essence of the Siddhānta

Investigation into the Essence of the Siddhānta

From those eighty-six original: ṣaḍaśīti; likely referring to the Ṣaḍaśīti-mukha, an astronomical period or a specific correction factor [units], the calculated ascendant sādhita-lagna; the point of the zodiac rising on the eastern horizon at a specific time is determined. In the manner described for the planetary positions in the yearly almanac, the desired time iṣṭa-kāla; the specific time elapsed since sunrise or the moment of observation is to be calculated. Here, the desired time should be based on the sidereal measure nakṣatra-māna; time calculated based on the rotation of the Earth relative to the fixed stars. Because of the calculation involving the civil/solar measure sāvana-māna; time based on the Earth's rotation relative to the Sun, there is a difference in the results.

From that time, according to the characteristics of the calculation... in the refined eighty-six calculations of the ascendant original: lagna, the second form of the time is considered most appropriate. This is the calculated result of the solar day... 23 ...In this way, for that reason, the directions should be followed according to the path described in the yearly almanac. Following the aforementioned method, the position of the night elapsed original: rātri-gata; the portion of the night that has already passed at the time of observation should be determined. Thus, even if there is an absence of the latitude/deflection śara; literally 'arrow', refers to the celestial latitude of a planet, the position on the ecliptic kānti-vṛtta; the Sun's apparent path across the sky remains central. Even if the calculation of the night elapsed from the ascendant is possible, this is the intended method.

Regarding the fourth [section], he describes the form of the Quadrant turya-yantra; an astronomical instrument used for measuring altitudes and time, consisting of a 90-degree arc:

Rāma

Now, the form of this tilted instrument trasta-yantra; a specific type of portable or pivoted sighting device is a quadrant. Its head, upper circumference, and corners are marked with the directions of space. There are transverse lines. From those lines, at the corners of the circumference, is the horizon line kṣitija-rekhā. Below the horizon line, on the upper circumference and the sides, apertures original: chidra; small holes for sighting should be made for easy observation. Between the horizon and the zenith original: kha-madhya, in the section of the circumference, at nine parts original: nava-aṃśa; nine degrees, the sunlight original: arka-tejaḥ enters simultaneously through the apertures.