NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Navigation exercise
From: John Cole
Date: 2008 May 19, 07:05 -0700
From: John Cole
Date: 2008 May 19, 07:05 -0700
JCA: Oops! I had written an Excel sheet to do the math and inadvertently entered the GMP (Greenwich Meridian Passage) instead of 12 while trying to write an algorithm to check whether before or after noon. Thank you for taking the trouble to give us some real celnav problems. Keep them coming. Some of us are busy with jobs that have nothing to do with navigation except avoiding traffic jams, and thunderstorms at Dallas/Ft. Worth, so we may not respond immediately. Thanks once again. John Cole On May 19, 12:22�am, Anabasi...@aol.com wrote: > JCA: > > I computed LAN= 12h 9m 42s by the equation of time method. �What am I doing > wrong? > > On 2008 May 16 meridian passage is 11h 56m and �ET 12h is 3m 38s. > Subtracting ET from GMP I get 11h 52m 22s. > > Your error John, is that you are applying the equation of time twice. � The > entry "Meridian passage" in the Almanac gives you the Local mean time (LMT) �of > meridian passage to the nearest minute. �This shows us whether �to add or > subtract the equation of time; in this case we will subtract. � The equation of > time entry gives us the actual difference between LAT and LMT of �meridian > passage of the sun to the nearest second. �In this case 1200 Local �apparent time > (LAT) minus 3m 38s to give us 11h 56m 22s for the LMT of mer. �passage. �This > of course must be converted to zone time, which you have �done in the next > step correctly. �I must note that I am unfamiliar with the �acronym "GMP" - JCA > > For Long 145d 40m E (-9h 42.6m) I get LMP 2h 9m 42s GMT. > > For �Zone -10 this becomes 12h 9m 42s. > > My other results are > > Az=0 > Ho= �86d 5.8m > Hc= 86d 4.2m > 1.6 toward > Lat= Dec-(90-Ho)= (19d 9.6m) - (3d �54.2m) = 15d 15.4m N > > **************Wondering what's for Dinner Tonight? Get new twists on family > favorites at AOL Food. � � � > (http://food.aol.com/dinner-tonight?NCID=aolfod00030000000001) --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
