The effects of atmospheric refraction on angles measured from a satellite

The refraction at a satellite is defined as the angle subtended at a satellite by the actual line of sight and the vacuum line of sight from the satellite to a point on the earth. If the satellite is assumed to be above the sensible atmosphere and if the well-known expression for astronomical refraction is accepted, the equations for the satellite refraction and the ‘first order error coefficients’ can be derived. Results of computations show that the refraction at the satellite is always less than 1.0 per cent of the total or astronomical refraction and that its sensitivity to changes in the independent variables is small. It is also shown that changes in the astronomical refraction have very little effect on the refraction at the satellite.