NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: John D. Howard
Date: 2019 Dec 1, 08:56 -0800
Mike,
The data are used for different things. The equation of time is used to convert from mean time ( watch time ) to apperent time. The time of medirian passage is for planing - when do you go up on deck for your noon shot.
Look at the data for today, Dec 1. EOT is 11m 06s and Mer. Passage for noon is 11:48. Also note that the GHA Sun for 1200Z is 2 D. 46.5 M. They all say the same thing but in different ways for different reasons. You use the GHA for sight reduction, the EOT to convert mean time to apparent time and the Mer. Passage to know about when to grab your sextant for the Noon shot.
Most of us, in this day and age, only use the GHA but if you do " Time Sights " to get local apparent time and then need to convert to mean time to get Longitude then you would use EOT.
Hope this helps.
John H. 41N 100W
