Signage-DakshinottaraBhitti

The instrument measures the Altitude of a celestial object as it crosses the Meridian. The circular arc of the west facing wall and the intersecting quadrants of the East facing wall have 90 degree Altitude marked at the bottom of the scale and 0 degree Altitude marked at the top ends of the scale.

The Dakshinottara Bhitti Yantra measures the Meridian Altitude of a celestial object, once in a day, as the celestial object crosses the Meridian.

The Meridian or the arc defined by the North, South and overhead point, is in this plane. With the rotation of the Earth, when a celestial body crosses this arc, halfway between its rising and setting times, it is said to transit the Meridian.

The angular height of the object from the Horizon, as it crosses the Meridian, is its Meridian Altitude.

Dakshinottara Bhitti is an instrument built into a wall placed exactly in the North-South direction.

The instrument uses either the semi-circular arc built into the west facing wall, or the intersecting quadrants of the East facing wall, to measure the Meridian Altitude of a celestial object.

The instrument measures the Altitude of a celestial object as it crosses the Meridian. The circular arc of the west facing wall and the intersecting quadrants of the East facing wall have 900 Altitude marked at the bottom of the scale and 00 Altitude marked at the top ends of the scale.

The markings on the scales are in units of degrees that have been further subdivided into 10 main divisions and further subdivisions of 3 small units which yield a least count of 2/ of arc for the instrument.

The Brihat Samrat Yantra is a sundial that can give the time to an accuracy of 2 seconds.

The shadow of the gigantic triangular wall, falling on the large circular arcs, tells the time. The triangular wall, with the angle inside the wall equal to the latitude of this location, is placed exactly in the North South Direction.

The shadow of the triangular wall moves equal distances in equal time intervals, on the circular arcs. This movement is calibrated to read the time. The arcs are divided into 6 hours each, for the morning and the afternoon segments. The hours are sub divided into 1 minute divisions that are further subdivided into thirty 2 second divisions.

The correction factor to be added, for the day, is displayed in the observatory and can be used to convert the time obtained from this instrument, to the clock time.

The Uttarayana and Dakshinayana annual movements of the Sun can also be measured, using the Brihat Samrat Yantra. The scales marked on its triangular wall are for measuring Declination, the angular position of a celestial object with respect to the equator.