A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Bruce J. Pennino
Date: 2016 Mar 19, 09:30 -0700
Just thumbing through an old Eldridge Pilot Book and noticed table which shows " Sun's True Bearing (azimuth) at Rising or Setting". I'm sure this has been discussed before, but on the first day or spring and fall the sun rises at an azimuth true east 90 and sets at 270 degrees west. I'm at 42N 72 W where the local variation is 15 west. So I add 15 dgrees and the azimuth of sunset should be 285 degrees magnetic.
I never before noticed in the table that for every degree change in the sun's declination the true azimuth changes at sunrise and sunset by about 1.3 degrees. The table is for 38N to 44 N. Longitude does not matter. Of course the angle at sunrise and sunset is directly calculated using the standard azimuth equation with H equal to zero: Cos A = sindec/cos lat
Happy spring and best regards.