NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2015 Jul 11, 14:55 -0700
Bob,
Step 2.
For contrary name:
90° - X - L = Y Y<90° Y = Y
Greg Rudzinski
From: Bob Goethe
Date: 2015 Jul 11, 11:54 -0700Recently, Hanno Ix said:
Bygrave needs consideration of special cases, whereas the sin-cos SR yields valid results for all combinations of L, D, t.
What are the special cases for Bygrave, and what are the principles for addressing them?
Greg has helped me sort out how to make the equations work, as framed below. I have been able to use them so far, and get the results to agree with the same problem solved with Pub. 249.
But Hanno's allusion to "special cases" tells me that if I have been able to make all my problems work out so far, it is because none of my problems so far involve a scenario where I need to tweak my approach.
Here is what I am using:
Where...
d = declination of the GP
t = meridian angle
L = latitude of AP
Az = azimuth angle
X & Y = intermediate values
1. tan(d) ÷ cos(t) = tan(X)
arctan(X) = _____°
2. 90° - X + L = Y
If Y > 90° then Y = 180° - Y
Y = _____°
