NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2010 Mar 18, 10:07 -0400
Hi Frank
Does your c.1840 Octant include a back sight? With your location on the western shore of Lake Michigan, an afternoon observation would seem to require a back sight.
I remain fascinated by a back observation of objects. The navigational astronomers (with no practical experience
J ) seem to indicate that this had fallen out of favor. What do the practical navigators say in their navigational logbooks? It
does seem technically possible and the existence of octants with a back sight feature confirms that (why add a feature that cannot ever be used).
For example, when I measure the star to star distance between Polaris and Sirius (distance on the order of 106+ degrees), this is essentially a back sight, since the angle is greater than 90
degrees.
Best Regards
Brad
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