At 12:59 22.6.2003 +0100, Chris Marriott wrote:

>I see you're in Belgium, Laurent, and that's probably why you use the "zero
>at south" azimuth convention. It seems as though it's normal to measure
>azimuth from south in the French-speaking parts of the world, whereas
>English speakers measure it from north. I guess it's just one of those
>"historical" things!

Hi,

only my 2 cents here. In Czechia I've learned in school about two kinds of
definitions for azimuth:

- astronomical; this one is defined as having zero point at south
- geographical (nautical); this one is defined as having zero point at north
- both running in the same direction (so only different by 180 degrees)

Check however Jean Meeus's Astronomical Algorithms, p.87/88, and you will
see, how problematic it was in past. Not even south or north point was
arbitrary, but also direction of measure ...

I would say that astronomically speaking azimuth had in last decades
settled on counting from south westward. But still counting from north is
often met and for many purposes it's more convenient. Nothing definitive here.

Best regards, jan

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