NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
2-Body Fix -- take three
From: John Karl
Date: 2009 Nov 8, 07:42 -0800
From: John Karl
Date: 2009 Nov 8, 07:42 -0800
Starting third post on this subject because the topic switched again. Here's my latest take: It should be apparent both from Fig 7.3 and from Eqs 7.5a-e, that these five equations do not contain information on the zero of longitude. Thus they can not determine longitude, which must be determined from another source -- such as the navigator. The navigator should label the body that is clearly off his meridian as GP1, the longitude reference body. Then if this body has its LHA greater than 180, of course, that solution should be picked as the inverse cosine in Eq, 7.5e. (We're using the convention that LHAs are measured westward to 360, and that west Lons are negative. Fig 7.3 will have its LHA2 corrected in the next printing.) If both bodies are too close to the ship's meridian to eyeball their LHA, the navigator should look around for other ones. JK --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com -~----------~----~----~----~------~----~------~--~---
