NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: accuracy of Cook's lunars
From: Lu Abel
Date: 2012 Dec 31, 12:01 -0800
From: Lu Abel
Date: 2012 Dec 31, 12:01 -0800
Half a mile accuracy? I think even the experts on this list would say that with a high-quality sextant and good observing conditions you might get a minute or two of error on land, more at sea, not 30 seconds.
Frank or some other expert on Lunars can confirm this, but I believe one is lucky to get time to ten seconds or so even under the best conditions with lunars. Given that the earth rotates 15 minutes of latitude per minute of time, that says one is likely to have a errors of a several minutes just due to the challenges of using lunars as a time-telling mechanism.
Last but not least, let's remember that Cook was using an octant and hand-calculated tables, not 20th century precision sextants and 21st century computer-generated celestial tables.
Frank or some other expert on Lunars can confirm this, but I believe one is lucky to get time to ten seconds or so even under the best conditions with lunars. Given that the earth rotates 15 minutes of latitude per minute of time, that says one is likely to have a errors of a several minutes just due to the challenges of using lunars as a time-telling mechanism.
Last but not least, let's remember that Cook was using an octant and hand-calculated tables, not 20th century precision sextants and 21st century computer-generated celestial tables.
From: Tom Sult <tsult@mac.com>
To: NavList@fer3.com
Sent: Monday, December 31, 2012 11:05 AM
Subject: [NavList] Re: accuracy of Cook's lunars
The interesting thing about this (besides the multiple ocular injuries) is that Cook was happy with his estimate of 30 min of error. Here on nav list one would think an error of 30 sec is at the upper edge.Very nice video. I recommend an A.Tom Sult
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