Question: Calculate the Longitude of the Ascending node for a satellite of Tundra Orbit. Satellite's longitude of perigee is 21.8 degrees and its argument of perigee is 270 degrees. Satellite must cover an Earth station with 21.8 degrees longitude and 63.5 degrees latitude. My approach So my approach so far is like this: Suppose that Tundra orbit inclination is 63.4: azimuth of the earth base (b) = asin(cos(63.4)/cos(63.5)) ~ 90 degrees. dl = atan(sin(63.5)*tan(90)) = indeterminable but for Ω: l1 = l2 - dl. (l2=21.8 deg) I am not physicist and i don't get this, at all. If anyone could shed light please.