Thank you very much for your reply, are you suggesting the light curves around the world? I considered this but thought that only really happened at black holes, or have I misunderstood your response?
1. The refractive index of the Earth’s atmosphere is
n = 1.01 + α(R − r),
where α is a constant, r is the radial distance from the Earth’s centre and
R = 6.4 × 10^6 m is the Earth’s radius. By considering a path comprising a series of
total internal reflections or otherwise, find a value of α...