A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: John Pinto
Date: 2021 May 27, 16:47 -0700
So far I haven't seen a realistic example where using the NASR tables you get a large negative F value from a ship at Sea.
Other than the Polaris sight (which may not be realistic) can anyone come up with anything else?
I've been told the only realistic sights where F is negative is very low Sun sights of the Upper Limb at sunrise or sunset but I have not been able to produce a realistic example of this where the negative F is large, mostly -1° or -2°.
If there is no realistic examples of large negative F values, then step 8 in the NASR procedures and form for adjusting the Z2 value should be interpreted as three mutually exclusive cases:
1) F > 90 (and thus make Z2 negative) - I assume we are ignoring the sign of F in this case but I could be wrong
2) F is negative (and thus make Z2 = 180 - Z2)
3) All other values of F leave Z2 as is
Would someone please confirm or correct me on this?