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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Re Obtain a fix when you don't have an clear AP.
From: Stan K
Date: 2015 Jan 17, 09:34 -0500
From: Stan K
Date: 2015 Jan 17, 09:34 -0500
John,
Giving the AP ("historically...called the assumed position") the alternate designation of "Assigned Point" is a great mnemonic for what it actually is. I'll be telling this to my students from now on.
Stan
-----Original Message-----
From: John Karl <NoReply_JohnKarl@fer3.com>
To: slk1000 <slk1000@aol.com>
Sent: Fri, Jan 16, 2015 10:52 pm
Subject: [NavList] Re: Re Obtain a fix when you don't have an clear AP.
From: John Karl <NoReply_JohnKarl@fer3.com>
To: slk1000 <slk1000@aol.com>
Sent: Fri, Jan 16, 2015 10:52 pm
Subject: [NavList] Re: Re Obtain a fix when you don't have an clear AP.
I don't get what the last few posts are trying to accomplish. The equation for LHA by John in post g30016 gives the longitude (via the LHA) on the LOP for the given latitude. With no iterations that lat & lon is an exact position on the LOP. That's all that possible to know from a single Ho observation. And of course you can compute as many of those exact points as you wish -- even to the point of ploting the whole circular LOP by lats and lons. No AP is needed.
The point of the St. Hilaire method is that it gives the unique point on the LOP that is nearest to an Assigned Point, the AP. Historically. this point has been called the assumed postion, but that is a bad, and misleading, name for it. We assume nothing when we assign a point for the AP. This is discussed more in my book where the designation AP is used solely to correspond with previous writings.
J Karl
