Karka Rasi Valaya - the instrument on the back wall of the Misra Yantra
The Back wall of the Misra Yantra at the Delhi Jantar Mantar observatory
Solstice day observations of the movement of the shadow of the Sun on the dial on the back wall of the Misra Yantra has been systematically studied by observers from the Nehru Planetarium and the Amateur Astronomers Association, during the Summer Solstice days of 2005 and 2006. This instrument, in principle, seems meant for measurements of ecliptic longitudes of stars. However, the measurement of the shadow of the Sun on the Solstice day could yield detailed information about the masonary parameters of the back wall of the Misra Yantra. This study, using about 150 observed data points, has appeared in the September 2008 issue of the Indian Journal of History of Science - Rathnasree, N., Anurag Garg, Arpita Pandey & R. K. Chikara, “Karka-Rasi-Valaya – The instrument on the back wall of the Misra Yantra,” IJHS 43.3 (2008) 425-436.