Indian Astronomical Astrolabe

Timeline

1. c. 499–550Kurukshetra · HaryanaIn Book IV 'The Sphere' (Golapāda) of the Aryabhatiya, Aryabhata described the armillary sphere (gola) model and methods using sundials, gnomons, and other devices to determine stellar positions and planetary motions, forming the theoretical foundation of Indian astronomical instrumentation.
2. c. 505–587Ujjain · Madhya PradeshVarahamihira described various astronomical and astrological instruments in works such as the Brihat Saṃhitā, including water clocks, sundials, and devices for determining the ecliptic, reflecting that 6th-century Indian astronomical observation had shifted from purely theoretical calculation to practical instrumental work.
3. 501–600Astronomical observation centers of northern India · Uttar Pradesh6th-century Indian astronomers used rotatable disc-like yantra to determine the altitude and azimuth of celestial bodies, functioning similarly to the later astrolabe: projecting celestial coordinates onto a flat disc and using an alidade to read the hour angle of stars, for calendar conversion and astrological deduction.