Azimuth 0, once more

Bruno Tilgner (Bruno_Tilgner@compuserve.com)
Wed, 23 Apr 1997 17:32:36 -0400

I have checked a number of European textbooks in several languages: The vast
majority define azimuth 0 as south for astronomical purposes. Some of them
mention that in navigation and geodesy the azimuth is counted from north.

I believe that counting from south has practical reasons: the angle between
the meridian and a star can be measured more easily in the south than in the
north because most if not all astronomical observatories are equipped with an
instrument that is accurately aligned due south (a "meridian circle") and is
primarily used to measure a star's declination. An alignment and measurement
from the north would be much more difficult to implement because a star's
lower culmination is generally not observable except for circumstellar ones.

Bruno Tilgner

Bruno_Tilgner@compuserve.com