NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Old style almanacs from new machines
From: Frank Reed CT
Date: 2006 Nov 16, 02:25 EST
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From: Frank Reed CT
Date: 2006 Nov 16, 02:25 EST
Ken M you wrote:
"Basically, the program creates a text file for a given month with all the
ephemera of the old almanacs. You can get the same thing from Frank Reed's
web-based almanac; this just gives you a monthly printout. When I first
wrote it I tested a bunch of random dates against Frank's almanac and they
agreed, but really, you would have to be completely insane to use
something like this for actual navigation, so the testing hasn't been very
rigorous. I wrote it just for the fun of calculating lunars by hand, much
as it was done ca. 1800, but using my own sights rather than historical
data. "
ephemera of the old almanacs. You can get the same thing from Frank Reed's
web-based almanac; this just gives you a monthly printout. When I first
wrote it I tested a bunch of random dates against Frank's almanac and they
agreed, but really, you would have to be completely insane to use
something like this for actual navigation, so the testing hasn't been very
rigorous. I wrote it just for the fun of calculating lunars by hand, much
as it was done ca. 1800, but using my own sights rather than historical
data. "
I see that your values agree with the ones in my online almanac exactly
about 75% of the time and differ by one second of arc about 25% of the time.
Both are accurate well beyond the necessities of the various navigational
methods, including lunar distances. Round-off error alone would have us disagree
at the one arc second level about one-sixth of the time. I guess
the additional 9% comes from small differences in the way we've coded
the almanac data. :-)
Looks nice, too. I got a kick out of your "traditional" star
names for the navigational stars.
You say that someone "would have to be completely insane to use something
like this for actual navigation". Isn't that one of our goals on the
list?!
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
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To post to this group, send email to NavList@fer3.com
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