Table of Contents
Assumed Longitude and the Meridian Angle
Let me take another stab at assumed longitudes and meridian angles for when you are in the eastern hemisphere. If you are in the eastern hemisphere, and the GP is also in the eastern hemisphere then you could:
If you are in the eastern hemisphere and the GP is in the western hemisphere, then:
In either case, once you have your aλ, if it is more than 30' away from your DR, you may adjust the whole-degree portion of your aλ (and consequently, the meridian angle) to get the aλ closer to the DR. This should keep your intercepts shorter, and may contribute to a slightly more accurate fix.
For instance, if you are in Caesarea and your DR λ is E 34° 53.5' and your aλ is initially 34° 02.8', with a meridian angle of W 22°, you might elect to modify your aλ and make it 35° 02.8', giving you a meridian angle of W 23°.
The above is the best I can do...but you may find our textbook more helpful. It addresses this in the lower left corner of page 152.
Since that is a pretty brief treatment, I am including some pages from a textbook I used back in the early 1980s.