A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Resetting your clock at a known location
From: Robert VanderPol II
Date: 2015 Oct 21, 11:36 -0700
Since we are “talking” historically, I have a question regarding resetting your clock when at a known location (or with a excellent fix , say from stars). This is discussed by Letcher & Karl.
Background: In August, a couple of hours before sunset when the sun was about due west, I pretended I did not know my time. I recorded an ordinary set of sights....really no special pains taken. Knowing my location, by initially guessing a time ( I knew it was a couple of hours before sunset) I quickly calculated my actual time. I recollect it was in error by a minute or less. If I did it again the next day, I suspect I could eventually get to 15 or 20 seconds error. Did mariners in the 1800s do this? So much easier than lunars and it can be done with any celestial body. This is nothing but a bit more than a “time sight” with some tabular interpolation. Anyone done this? How accurate was your time when at a known position? Karl’s method of interpolation is straight forward.
Letcher discusses this in his book on HO-208. He also provides and alternative method for performing Lunars which would work at an unknown location without an accurate time to start with.
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