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Re: Hypothetical Exercise - Abducted By Aliens
From: Dave Walden
Date: 2008 Jun 17, 09:30 -0700
From: Dave Walden
Date: 2008 Jun 17, 09:30 -0700
My sources were: "James A. Van Allen, Basic principles of celestial navigation, American Journal of Physics -- November 2004 -- Volume 72, Issue 11, pp. 1418-1424." and "Michael Dorl wrote- | Back in 1999, I sat down and worked out the spherical trig for this | problem. It may be found at | | http://ns.doit.wisc.edu/~mdorl/Sight%20Reduction%20write%20up.doc | | I am pretty sure it handles all the quadrant problems I did not consider | problems at angles when the trig functions misbehave." On Jun 17, 1:22�am, Geoffrey Kolbewrote: > Very nice. I hope these aliens gave you a rubber dinghy so you can paddle > to Pearl Harbour :-) > > To save reverse engineering the spread sheet, what were the analytical methods? > > Geoffrey Kolbe > > At 01:29 17/06/2008, you wrote: > > > > >You really know quite a lot. �If it's 0600GMT (approx their morning > >twilight) and it's your evening twilight, you must be approx 12 hours > >different, or the other side of the world. �Plot the Ground Points of the > >three stars as on the attached. �For latitudes up to the give 30 deg N, > >the distortions aren't outrageous. �Draw the Zenith Distance Circles of > >Position. �Spica is about the right length since it's North-South. �Since > >Vega-Pollux intersect somewhere not too far from north of Spica and are > >mostly East-West, scale the lenghts on this plot by 1/cos(Lat). �So AP > >could be somewhere near 25N, 157W. > > >But no AP is needed it you're willing to do some math. �The attached > >spread sheet shows two analytic methods (which, luckily give the same > >answers). �It can be seen, the 3 intersection points are: �23-18.4N > >157-17.5W, 23-18.4N 157-17.5W, and 23-18.3N 157-17.6W- Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---