Kshithija, the Celestial Horizon!

The formula for computing the Ascendant is


Tan L = Sin E / cos E cosw - Sin w Tan A


The Ascendant is a point on the Celestial Horizon. The Eastern Celestial Horizon

First compute E, the Right Ascension of East Point, the East Point lying on the Celestial Equator and this E is subjected to the trignometric correction referred to as above.

The Celestial Horizon is known as Kshithija. w is the maximum declination of the Sun, The Soorya Parama Kranthi. A is the latitude of the place.

The Eastern Point on the Celestial Horizon is Udaya Lagna
180 degrees from it is the Astha Lagna or the Descendant