NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Byron Franklin
Date: 2010 Jun 2, 15:43 -0700
The question of accuracy between Azimuth and Amplitude is a no contest.
Navy Ships at sea must determine gyro error every day. However in rough seas the leveling bubbles are
difficult to line up. In the end a best estimate can result with a false bearing of the sun, sometimes as much as two degrees. The Azimuth circle is delicate mirrors may easily be out of line. The higher the sun the more the error, on the other end the sun bearing by telescope alidade and the lower sun, is much more accurate even if it is an Azimuth. More accurate is the Amplitude with the sun a semi-diameter above the horizon. (Because of refraction.)The lower limb is about 16’ high the eye can estimate well enough because the sun is going an away or toward you changing very slowly while in low latitudes.
I still have my HO 71 tables red Azimuth tables. Mr. Brown of the Hydrographic said (about 1970?)that they were to drop the Publication because above 60 North the accuracy decreased. I would suggest that you would if under the right circumstance, use my bearing technique to find compass error, take an Azimuth and Amplitude. And compare them using my technique as zero. The Azimuth at open sea is fine for ship heading, but can cause problems with harbor fixing.
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