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Series of Sun sights in relatively rapid succession
From: Andr�s Ruiz
Date: 2008 May 28, 10:56 +0200
From: Andr�s Ruiz
Date: 2008 May 28, 10:56 +0200
In a beta version my software CelestialFix, a simplified algorithm of Kaplan's [1] is implemented, (the core of the STELLA [2] USNO software, used with a star-tracker). Sights have inside information about the position, course and speed of the observer, and the algorithm solves the general problem in an engineering way. One of the great advantages is that the advance of the circles of equal altitude is taken into account automatically. I have tested it with a simulator and the solutions are good solving for position, and for position & motion. With real sights: ten taken over 40 min aboard a sailboat, 3/5 Kt, the solution for position is really good, but it isn't when including motion, I think because the course and speed were not constant during the time of shooting the Sun. Is it very difficult to maintain a constant motion when sailing. Aboard a motor vessel, freighter, ..., the thinks maybe go well, but I don't know... For someone who wishes to test the program, I can send it by e-mail under request (5.7 MB) Andr�s [1] Kaplan, G. H. (1995): "Determining the Position and Motion of a Vessel from Celestial Observations", Navigation, Vol. 42, No. 4, pp. 631-648. [2] http://www.dtic.mil/dticasd/sbir/sbir021/n104.pdf -----Mensaje original----- De: NavList@fer3.com [mailto:NavList@fer3.com] En nombre de frankreed@HistoricalAtlas.net Enviado el: domingo, 25 de mayo de 2008 13:41 Para: NavList@fer3.com Asunto: [NavList 5129] Re: Navigation exercise By the way, have you ever considered the general problem of taking a series of Sun sights in relatively rapid succession (at an arbitrary time of day, not necessarily around noon)? For example, suppose it's 1500 local time. If I take ten sights over half an hour, what kind of position fix can I get? This is a generalization of the "sights around noon" problem. There's no easy graphical solution but it's similar in other respects. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---