Question

The parameter 'Drigansha' (Azimuth) is measured on which celestial circle?

• A. Kshitijavritta (Horizon)
• B. Konavritta (Vertical Circle)
• C. Drigvritta (Vertical Circle through planet)
• D. Yamya-uttaravritta (Meridian)

Hint:

Think of a compass. A compass tells you the direction (Azimuth) by looking at the flat ground (Horizon). Therefore, Azimuth is a horizontal measure.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
In horizontal coordinates, the position of a celestial body is defined by two angles: Altitude (Unnatamsha) and Azimuth (Drigansha). Altitude is the height above the horizon, and Azimuth is the direction along the horizon measured from a reference point (usually North or South).

Step 2: Detailed Explanation:
1. Kshitijavritta (Horizon): This is the circle that separates the visible sky from the Earth. The angular distance from the East or South point to the vertical circle passing through the planet is measured along this circle. Therefore, Azimuth (Drigansha) is an arc of the horizon.
2. Drigvritta: This is the vertical circle passing through the zenith and the planet. It is used to measure the Altitude, not the Azimuth itself (though the Azimuth marks where this circle hits the horizon).
3. Yamya-uttaravritta (Meridian): This is the circle passing through North, Zenith, and South. It is the reference for midday but not the circle for Azimuth.

Step 3: Reasoning:
Just as terrestrial longitude is measured along the Equator, celestial Azimuth is measured along the local Horizon (Kshitija). In Indian astronomy, Drigansha is often measured from the East-West line or the North-South line on the horizon plane.

Step 4: Final Answer:
Drigansha exists and is measured on the Kshitijavritta (Horizon).