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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Very Small Altitude-Accurate Results
From: Hewitt Schlereth
Date: 2015 Aug 10, 13:18 -0700
From: Hewitt Schlereth
Date: 2015 Aug 10, 13:18 -0700
Bruce, my rule was if I could see it I shot it. Probably a bit of happy chance there, but hey, rejoice.
Authority says not to take sights below 15 degrees or in moonlight. I've done both when the opportunity presented, and so far as I could tell (checking against the DR) had perfectly normal results.
FWIW re authority: there is an ancient Roman adage "nulius verba," i.e., "don't listen," or "oh yeah, sez who?" :-)
BTW, next time the sun is low for you, you might wait a bit and try a sextant-less sight. Time the sunset. That's Hs of zero degrees. It's fun. All you need is your eyes and your watch.
Hewitt
Hello:
Yesterday I did a LL sight just before sunset ( got delayed in traffic). Normally I try to have Ho greater than 10 degrees. My average Ho was 4 degr 35.2 minutues.I was shocked when my LOP went virtually through my position. Using my known latitude, I did a time-sight calc for longitude. Longitude was calculated to be 1 minute of actual longitude . Were my measured results just good fortune? Did the dip from table luckily coincide with dip for the atmospheric conditions? There was a crisp horizon and I was extra careful in "swinging" the instrument. My height of eye was only 14 ft, so dip angle was small. Anyone had good/bad results at very small angles??
Bruce
