NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Navigate by Skyline
From: Bill Ritchie
Date: 2022 Aug 31, 18:39 +0100
From: Bill Ritchie
Date: 2022 Aug 31, 18:39 +0100
Rafael,
You asked "I would be very grateful if any of you ... would point me to a source where I may find this derivation, or to an alternative equivalent algorithm.
This first link is an online calculator for the intersection problem using Great Circle methods. It also gives the formula used (with faint comments on right of page) and, later on, associated JavaScript source code.
Plugging in Frank's positions of E.S.B (40.57297, -73.9844) and 550 Madison:(40.7615, -73.97308), together with bearings 179.69569 and 181.40256, it agrees with Frank's position, as one would expect. (I calculated the above initial GC bearings using Franks other two positions - the code could be modified to input 4 positions and calculate the initial bearings automatically.)
This second link is the same author's preferred approach using vector methods.
Alas, neither really answer your 'derivation' request.
Regards,
Bill Ritchie.
2909nm from ESB on initial GC bearing of 053.25°.
On Tue, Aug 30, 2022 at 4:46 AM Marty Lyons <NoReply_MartyLyons@fer3.com> wrote:
I pretty much agree the position found by Don Seltzer. Being from NJ, I know the area well. I did a lot of windsurfing in Sandy Hook Bay.
