The Yantra Raj, is an adaptation of an astrolabe - a medieval instrument for measurement of time and the positions of celestial objects. The Yantra Raj was made specifically for latitude of 27 degrees and has some of the movable segments of the standard astrolabes, built in as part of the base plate. It has a separate attachment for a sighting tube, to determine altitudes of celestial objects.
The instrument, in principle, could be used for measuring Time, positions of the Sun and that of some celestial objects in the sky and could also be used for help in computations of celestial positions and their changes. The instrument could be used for measuring the time - using the positions of stars in the night time, and, using the position of the Sun in the daytime.
The Northern unit of the Yantra Raj is incomplete.