[Therion] Declination and meridian convergence
wolfgang.zillig at web.de
Tue Oct 4 17:51:37 CEST 2011
I'm a little bit confused at the moment how to correct for declination
and meridian convergence.
Question 1: Is it correct that in therion and in survex the declination
is specified exactly the opposite way?
Therion handbook page 18:
true bearing = measured bearing + declination
Survex 1.2.1 manual page 19:
(true bearing)=((bearing)-(declination zero err))
So in case that magnetic north is 2° east of geographic north, I have to
correct this in therion by -2 and in survex by +2.
If this is correct, could you please add a warning note to the therion
When I enter the measurement data in therion, the meridian convergence
is handled automatically (in case a "cs" is specified). However due to
historic reasons most of our data is still in survex format. I import
the ".3d" file and specify the "cs" during import. I assume that therion
is not applying any corrections for the meridian convergence and I need
to correct the bearings manually in survex?
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