Answer : 3. "जयपुर के सवाई जयसिंह"
Explanation :

1. In 1725 AD, Sawai Jai Singh II made a pure table of constellations ‘Jij Muhammad Shahi’ and composed an astrological book named ‘Jai Singh Karika’.

2. Sawai Jai Singh built a big observatory, Jantar Mantar, in Jaipur in 1734 AD, which is the largest observatory in the country.