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Re: Time sight primer
From: Doug MacPherson
Date: 2019 Sep 26, 09:12 -0700
From: Doug MacPherson
Date: 2019 Sep 26, 09:12 -0700
Hi Chris:
I calculated the longitude using your data and the traditional "time sight" formulas. I used the 2019 Nautical Almanac for GHA and Dec, and Norie's Natutical Tables for the calculation data (Logs. of Trig. Functions Tables, Haversine Tables, and ABC Tables for Azimuth). I did calcutlate the Azimuth so that I could turn the single point position into a Line of Position.
Based on your data, my calculated longitude was 1.1' different from your GPS position. My Azimuth of 267.3° is right in line with the U.S.N.O.'s 267.6°. Your H.O. compares very favorably with the U.S.N.O. calculated Hc for the Sun at the time and place that you took your sight. That was a nice shot.
My calculations and the U.S.N.O. data is attached.
Cheers,
Doug
