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MSG/SEVIRI -- Reflectance


MSG_hdf_count_to_reflectance.png
(Above information came from www.eumetsat.int )

#3 : d(t), Sun-Earth distance in Astronomical Unit (AU).

If t is the day of the year, then

     M = 0.9856*float(t-4)* pi / 180.
     d(t) = 1.-0.01673*cos(M)
MSG_sun_earth_distance.png
AU, which stands for "astronomical unit", is a unit for measuring distance. One AU is the average distance from the Sun's center to the Earth's center. It is equal to 149,597,871 km (92,955,807 miles).