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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Winter Sextant Sight Accuracy?
From: Trevor Kenchington
Date: 2002 Jan 11, 6:01 AM
From: Trevor Kenchington
Date: 2002 Jan 11, 6:01 AM
Jared Sherman asked:
> But not to digress...the basic question was and still is, what kind of
> position accuracy is anyone else getting with winter sextant sights at
> lattitudes above 40� ?
On a Nova Scotian beach (latitude just shy of 45 North) under winter
conditions, I expect to get a position within one mile, using a plastic
sextant -- given care to allow the instrument to cool to air temperature
while exposed to the Sun (thus allowing it to equilibrate with the
combination of air temperature and radiant heat).
However, mirage effects can distort the apparent position of the
horizon. My one attempt to take sights across an ice-covered harbour, in
bright sunlight and with a low height of eye, produced spectacular
errors!
Trevor Kenchington
--
Trevor J. Kenchington PhD Gadus@iStar.ca
Gadus Associates, Office(902) 889-9250
R.R.#1, Musquodoboit Harbour, Fax (902) 889-9251
Nova Scotia B0J 2L0, CANADA Home (902) 889-3555
Science Serving the Fisheries
http://home.istar.ca/~gadus
