NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Where is the Prime Meridian?
From: Murray Peake
Date: 2021 Dec 10, 11:12 -0800
From: Murray Peake
Date: 2021 Dec 10, 11:12 -0800
I'm interested in the practical achievable accuracy for finding the time given the position - a problem discussed in Henry Raper and John Letcher offers an approach as well.
I was checking the accuracy of the Maritime Positions in Raper and looked at Greenwich Observatory which is in the tables, rather naturally at 0 degrees longitude. When I look at Google Maps though the Prime Meridian seems 2 arc seconds displaced from the Observatory buildings in Blackheath Avenue. How did that happen?
Raper's quoted positions are to the nearest minute of longitude which I suppose limits the accuracy to 4 seconds of time. Is that the limiting factor given usual sextant accuracy and observaional errors in an artificial horizon?
Best Wishes
Murray
