A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Bob Crawley
Date: 2015 Nov 4, 07:23 -0800
Geoffrey - what you say makes sense so I double checked. Another Occultation site I tried broadly agreed with the Orwell Observatory and Stellararium (why didn't I use that before!) shows the same occultations. I can't see my mistake, although that's the most likely answer even though Frank's calculator seems to agree.
At first I thought it might be some odd parallax effect because is Azimuth is around 100d but then I sketched out the triangle and think it may be because the triangle is long and thin and that the parallax correction is large relative to the semi diameter. I've attached a sketch and have used Bruce Stark's notation. Have to have a rest now!