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Author
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Topic: Latitude by Polaris -- fine tuning
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David Burch
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posted November 08, 2004 09:41 AM
In the course materials in section 11.10 it says, in step 6, to round of the LHA Aries to the nearest whole degree to enter the Polaris Tables.
This is not actually the best way to do this. It is best to use the actual LHA you determine from your DR, ie look up GHA Aries for the time of the sight, then subtract your west DR-Lon from that to get the actual LHA Aries, degrees and minutes and then go into the tables with that value and interpolate for the proper LHA.
That is the way the Nautical Almanac instructions have it, and that is indeed the best way to do it. We are unnecessarily throwing away precision (as much as 0.3' in the worst case) if we use the short cut given in the course materials.
We will fix this on the next printing.
From: Starpath, Seattle, WA
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