Calculations of refraction angles based on the homogeneous model of the atmosphere.

An approximate formula for calculating refraction angles for arbitrarily long slant paths is derived within the framework of the spherically homogeneous model of the atmosphere. In order to take refraction into account when viewing extraterrestrial objects (H > 50 km), an exact formula is derived, which enables one to calculate the refraction angles to within the error in the astronomical refraction, either measured or calculated. The applicability limits of the formulas obtained are discussed and estimates of their accuracy are given.