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Sunday, May 8, 2011

More celestial nav on-the-cheap

I've been assuming the use of the current year's Nautical Almanac, which retails for $30. However, the seven-star method of Pub 249 volume 1 is also a self-contained system which can be used anywhere, and it happens to retail for about $20, eliminates sight-reduction tables entirely and also affords very simple precomputation of your sights without a starfinder. And it is fair to say that the NAO sight reduction tables in the Nautical Almanac are a step above simple celestial techniques.

Personally, I would want to be able to use the bright objects in the sky, specifically the sun, moon and planets, so I would choose the NA. But one could certainly live without these, and 249 vol 1 is actually much easier to use, and good for ten years. So for our purposes, I'm going to knock another $10 off our total cost.

By the way, my ultimate intention with all of this is that once I'm comfortable with the methodology of using very inexpensive tools for celestial navigation, I'm going to actually test it from a small boat somewhere in the Salish Sea, and see how accurate the position I derive is from this. Hopefully by the end of the month I'll have enough data to establish a trend with the watch, and then I'll let it generate out for another 20 days beyond that.

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