Astronomy
T1
Surya-Siddhanta IV.12-13 (~5th c. CE) gives an explicit formula for the half-duration of a lunar eclipse: take the squared lunar latitude, subtract from the squares of the (sun+moon radii) and (sun−moon radii), root, multiply by 60, divide by the difference of daily motions. The geometric structure is identical to the modern eclipse-timing calculation. Pre-telescopic Indian astronomers could predict eclipse start, totality, and end to within minutes.
From the source
“These, multiplied by sixty and divided by the difference of the daily motions of the sun and moon, give, in nadis, etc., half the duration (sthiti) of the eclipse, and half the time of total obscuration. ”
Well-supported