A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David C
Date: 2020 Aug 23, 02:03 -0700
A further thought..... even if I had remembered that I had Stelarium on my PC I may not have used it. Doing the calculation manually gave me the satisfaction of understanding the principles. Here is what I did:
Some plane trionometry to determe the sun's altitude.
Looking up dec and eot in some old tables.
Calculating apparant time with the sundial formula.
Looking at the direction of the "shadows" and deciding that it was post meridian.
Applying eot to get mean time at the 180th meridian (GMT + 12).
I am not on the 180th meridian so I applied a longitude correction - in my case about 20 min (time).
Even though the calculated time is approximate due to the uncertainty in the sun's altitude it was very satisfying to obtain a result that made sense.