The Astronomical Observatories of Jai Singh c5.9

c5.9

⁵ The polar longitude is marked on the ecliptic by the circles of declination, that is, the difference (Δλ) between the true longitude (λ) and polar longitude (λ') is that portion of the ecliptic intercepted between the star's declination and latitude circles. The polar latitude β' (which is not given in the MS.) is, similarly, the part of the declination circle between the star and the ecliptic. The change of co-ordinates can be made by help of the following formulæ (i) tan M = cos ω / cos λ (ii) sin λ' = sin M. sin χ (iii) sin Δλ = tan λ cot M.