--- "Matson, Robert" <ROBERT.D.MATSON@saic.com> wrote: > There is no need to complicate your analysis by computing refraction. > For a ground-based observer, refraction will bend the light rays > from the Sun, Venus and ISS by equal amounts. Thus, the apparent > position of ISS relative to the Sun/Venus would be identical, even > if the earth had no atmosphere. Rob is correct, as usual:) The iss would not shift with respect to the sun, because of refraction, so I am not sure why you thought it would. > > By far the greatest source of uncertainty in the ISS transit calculation > is the accuracy of the TLE itself. For example, one big solar outburst > in the next day or two would change all your predictions. > Again correct. There's a gps antenna installed on one of the trusses of the iss, and the reciver on board determine's the iss position to around an estimated 100 m, I read somewhere. One problem is the iss is made of metal, so the multipath is bad:) So the position of the iss is a big factor in the calculation, then for path width, there the uncertainty in the size of the sun/moon and it effect on the calculation. I read the sun is been thought to change size even if slightly. I remember they were trying to use solar eclipse's to see what going on. Just my option. Kevin __________________________________ Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/ ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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