page_title: Jantar Mantar, Jaipur
section_title: Description
hierarchical_section_title: Jantar Mantar, Jaipur / Description
caption_attribution_description: English: The Yantra Raj, is an adaptation of an astrolabe - a Medieval instrument for the measurement of time and positions of celestial objects.
context_page_description: The Jantar Mantar is a collection of nineteen architectural astronomical instruments built by the Rajput king Sawai Jai Singh I, the founder of Jaipur, Rajasthan. The monument was completed in 1734. It features the world's largest stone sundial, and is a UNESCO World Heritage site. It is located near City Palace and Hawa Mahal. The instruments allow the observation of astronomical positions with the naked eye. The observatory is an example of the Ptolemaic positional astronomy which was shared by many civilizations.
  The monument features instruments operating in each of the three main classical celestial coordinate systems: the horizon-zenith local system, the equatorial system, and the ecliptic system. The kanmala Yantraprakara is one that works in two systems and allows transformation of the coordinates directly from one system to the other.
  The monument was damaged in the 19th century. Early restoration work was undertaken under the supervision of Major Arthur Garrett, a keen amateur astronomer, during his appointment as Assistant State Engineer for the Jaipur District.
context_section_description: The observatory consists of nineteen instruments for measuring time, predicting eclipses, tracking location of major stars as the earth orbits around the sun, ascertaining the declinations of planets, and determining the celestial altitudes and related ephemerides. The instruments are (alphabetical):
  Chakra Yantra (four semicircular arcs on which a gnomon casts a shadow, thereby giving the declination of the Sun at four specified times of the day. This data corresponds to noon at four observatories around the world (Greenwich in UK, Zurich in Switzerland, Notke in Japan and Saitchen in the Pacific); this is equivalent of a wall of clocks registering local times in different parts of the world.)
  Dakshin Bhitti Yantra (measures meridian, altitude and zenith distances of celestial bodies)
  Digamsha Yantra (a pillar in the middle of two concentric outer circles, used to measure azimuth of the sun, and to calculate the time of sunrise and sunset forecasts)
  Disha Yantra
  Dhruva Darshak Pattika (observe and find the location of pole star with respect to other celestial bodies)
  Jai Prakash Yantra (two hemispherical bowl-based sundial with marked marble slabs that map inverted image of sky and allows the observer to move inside the instrument, measures altitudes, azimuths, hour angles, and declinations)
  Kapali Yantra (measures coordinates of celestial bodies in azimuth and equatorial systems, any point in sky can be visually transformed from one coordinate system to another)
  Kanali Yantra
  Kranti Vritta Yantra (measures longitude and latitude of celestial bodies)
  Laghu Samrat Yantra (the smaller sundial at the monument, inclined at 27 degrees, to measure time, less accurate than Vrihat Samrat Yantra)
  Misra Yantra (meaning mixed instrument, it is a compilation of five different instruments)
  Nadi Valaya Yantra (two sundials on different faces of the instrument, the two faces represent north and south hemispheres, the accuracy of the instrument in measuring the time is less than a minute)
  Palbha Yantra
  Rama Yantra (an upright building used to find the altitude and the azimuth of the sun)
  Rashi Valaya Yantra (12 gnomon dials that measure ecliptic coordinates of stars, planets and all 12 constellation systems)
  Shastansh Yantra (next to Vrihat Samrat Yantra, this instrument is a 60-degree arc built in the meridian plane within a dark chamber. At noon, the sun's pinhole image falls on a scale below enabling the observer to measure the zenith distance, declination, and the diameter of the Sun.)
  Unnatamsa Yantra (a metal ring divided into four segments by horizontal and vertical lines, with a hole in the middle; the position and orientation of the instrument allows measurement of the altitude of celestial bodies) 
  Vrihat Samrat Yantra (world's largest gnomon sundial, measures time in intervals of 2 seconds using shadow cast from the sunlight)
  Yantra Raj Yantra (a 2.43-metre bronze astrolabe, one of the largest in the world, used only once a year, calculates the Hindu calendar) 
  The Vrihat Samrat Yantra, which means the "great king of instruments", is 88 feet (27 m) high; its shadow tells the time of day. Its face is angled at 27 degrees, the latitude of Jaipur. The Hindu chhatri (small cupola) on top is used as a platform for announcing eclipses and the arrival of monsoons.
  The instruments are in most cases huge structures. The scale to which they have been built has been alleged to increase their accuracy. However, the penumbra of the sun can be as wide as 30 mm, making the 1mm increments of the Samrat Yantra sundial devoid of any practical significance. Additionally, the masons constructing the instruments had insufficient experience with construction of this scale, and subsidence of the foundations has subsequently misaligned them. The samrat yantra, for instance, which is a sundial, can be used to tell the time to an accuracy of about two seconds in Jaipur local time. The Giant Sundial, known as the Samrat Yantra (The Supreme Instrument) is one of the world's largest sundials, standing 27 metres tall. Its shadow moves visibly at 1 mm per
caption: Yantra Raj
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