[A] I freely admit all these things could be lies. [N] That's all I'm after at the moment. [A] However, the burden of proof rests not on the various countries and space agencies but on you/us. [N] I accept that. [A] Then and only then could we put forward a proof that the accepted amount of refraction is incorrect You would have to prove that it is all a lie, not just state that you don?t accept it, based on your/our own assumptions. [N] You are correct. My statement was scientifically flawed. I should have prefaced it with, "In my opinion." Thank you for pointing this out. Neville. Send instant messages to your online friends http://uk.messenger.yahoo.com