NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2013 Jun 19, 19:02 -0700
Hi Geoff.
Yes, it's really just that simple. The "sign" is just a count of thirty-degree units. The only catch is reminiscent of an old issue in computing science: zero-based arrays. If you've done any coding, you know that you can have any array of a dozen objects. Arrays have been around for decades. But should a dozen objects be numbered from 1 to 12 or from 0 to 11? In modern arrays, they're almost universally numbered from 0 to 11. The "first" element is really the zero-th element. The same issue comes up with the numbering of the signs in old astronomical tables. The first sign is Aries. Should that be numbered sign "0" or sign "1"? It's simply a matter of convention. Once decided, you take the sign count (or sign count minus 1) and multiply by thirty. Then add the degrees. The result is the ecliptic longitude. You can look at it as an extension of the sexagesimal system: minutes are 60 times larger than seconds, degrees are 60 times larger than minutes, and (slightly breaking the pattern) signs are 30 times larger than degrees. From this perspective, the signs themselves are numbers. Aries is zero. Taurus is one. And so on.
-FER
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