NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Swinging the Arc
From: Frank Reed CT
Date: 2004 Dec 5, 16:23 EST
From: Frank Reed CT
Date: 2004 Dec 5, 16:23 EST
Does "swinging the arc" the wrong way (as discussed on the list recently)
work? That is, are there circumstances under which it will work more-or-less to
get the sextant vertical? I suppose the best way to decide would be to try it in
practice for various Sun altitudes using three different approaches:
1) No swing at all. This would serve as a sort of control.
2) Swinging the arc the "wrong" way by rotating about the line of sight to
the horizon. Sun's image moves back and forth across the field of view.
3) Swinging the "right" way by rotating about the line of sight to the Sun.
Sun's image remains essentially centered in the field of view.
For high altitudes, I am nearly certain that method 3 is going to give much
better results, but at lower altitudes maybe there isn't much difference. Anyone
care to experiment? I also wouldn't be too surprised if method 1 (doing nothing
at all --estimating sextant vertical visually) works reasonably well in many
cases, too.
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
[ ] Mystic, Connecticut
[X] Chicago, Illinois