Module equatorial 

Sun geocentric right ascension (α) and declination (δ). Sections 3.9 and 3.10.

Functions

geocentric_declination

δ = arcsin(sin β · cos ε + cos β · sin ε · sin λ) (degrees, signed, in [-90°, 90°]). Equation 31.

geocentric_right_ascension

α = atan2(sin λ · cos ε − tan β · sin ε, cos λ) (degrees, wrapped into [0°, 360°)). Equation 30.