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    Re: Out of Date Almanac
    From: Gary LaPook
    Date: 2009 Dec 10, 00:36 -0800
    I have attached excerpts from H.O. 249 containing a long term almanac for stars good through 2014 and for the sun through 2016. I have also included the Polaris correction table. Since the star positions, including Polaris, are for epoch 2010 you need to apply the precession and nutation correction to their LOPs, including the Polaris LOP, for years other than 2010. If he fix consists solely of stellar LOPs then you apply the P&N correction conveniently to the fix. If mixing star LOPs with other bodies then apply the P&N correction to the star APs prior to plotting the LOPs.

    Since the "Q" Polaris correction table is based on Polaris' epoch 2010 position you must also apply the P&N correction to the Polaris LOP. The way you do this is to treat Polaris like any other star, calculate Hc for it, compare it to Ho, measure off the intercept and draw the LOP. The way to compute Hc for Polaris is simple. You start with your assumed latitude, remembering that if Polaris were exactly at the pole then the altitude of Polaris would be equal to your latitude. The "Q" table makes the correction for the fact that Polaris is not exactly at the pole. Using your assumed longitude you calculate LHA Aries and enter the "Q" table. Then starting with your assumed latitude you apply the "Q" correction WITH REVERSED SIGN to the assumed latitude which results in Hc, the altitude you would have measured if you were at your assumed position. Then you plot the Polaris LOP in the normal way using the azimuth from the Polaris table and applying the P&N correction if necessary. If you are crossing the Polaris LOP only with other star LOPs then you apply P&N to the fix, otherwise to the Polaris AP.



    The almanac data derived with the H.O. 249 almanac has only one minute precision the same as the Air Almanac and not as precise as the Nautical Almanac or Kolbe's almanac.

    gl






    Greg Rudzinski wrote:
    Hewitt,
    
    The Bowditch long term almanac is not user friendly )-:
    
    On Dec 8, 9:33 am, Hewitt Schlereth <hhe...---.com> wrote:
      
    Greg, are you aware of the Bowditch long-term almanac. It's Appendix H
    in my 1975 green-cover edition of Volume II. It's just a couple of
    pages.  I seem to recall it was Appendix X in the blue-cover editions.
    -Hewitt
    
    On 12/8/09, Greg Rudzinski <gregrudzin...---.com> wrote:
    
        
    And I ordered Geoffrey Koble's Long Term Almanac which will compliment
     old almanacs to keep me going until 2050.
          
     On Dec 8, 5:43 am, Greg Rudzinski <gregrudzin...---.com> wrote:
     > Thanks Gary and Frank,
          
     > I will be using my 2006 Nautical Almanac for 2010 Sun observations
     > with no corrections and be within .5 MOA (good enough). For stars the
     > plan is to photo copy the online Nautical Almanac for
     > 1/1/10,3/1/10,6/1/10,9/1/10 and use the star SHA and declinations plus
     > a 2.1 minute GHA aries correction which should get me within .5 MOA
     > (good enough). Looks like I'm out of luck for the Moon and Planets
     > though. Any ideas on how to compensate the Nautical Almanac Polaris
     > table ?
          
     > Greg
          
     > On Dec 7, 5:10 pm, Greg Rudzinski <gregrudzin...---.com> wrote:
          
     > > Any opinions on using a Nautical Almanac that is four years out of
     > > date? I bring this up because there are old almanacs available on
     > > Amazon.com from $2 to $10.  New Nautical Almanacs have gotten
     > > expensive so my plan is to use a 2006 for the upcoming year 2010.
          
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