Streefkerk:   lat=51.90, lon=4.75
Winter = UTC+1, Zomer=UTC+2

Formules

sin δ = 0.39795 ⋅ cos [ 0.98563 ⋅ ( N – 173 ) ]
δ: declination [rad]
N: days since 1 jan
accuracy: +/- 1 deg

graph