Finding true south magnetically can be influenced by anything magnetic nearby. An alternate method is to use a vertical stick at solar noon and note the direction of the shadow as per this post.
That's 11 degrees to the East, or to your left when facing south.
Magnetic north is east of true north. So when facing south magnetic south is to the right of true south. You can buy compasses which allow you to adjust this offset (it's called magnetic declination) in the compass so you just point the compass to south.
I am new to this and it dont seem so easy.
I live in Rockingham W.A. and want to find true south. I have been to the Government site shown above and it gives me a reading of -4.634, however, someone else told me that I should point my compass due magnetic south and then the true south would be 12 degrees to the east of that. If the declination says -4.634, is that the difference, or 12 degrees. Is the -4.634 degrees or some other measurement.
Really - the shadow method at solar noon is the easiest. You only have to get it within 5 degrees or so as the adjustment on your mount will cover that much when you are drift aligning.
Use a plumb-bob with a thick-ish string and you won't need a stick in the ground
I am new to this and it dont seem so easy.
I live in Rockingham W.A. and want to find true south. I have been to the Government site shown above and it gives me a reading of -4.634, however, someone else told me that I should point my compass due magnetic south and then the true south would be 12 degrees to the east of that. If the declination says -4.634, is that the difference, or 12 degrees. Is the -4.634 degrees or some other measurement.
Place Names Search Results
NAME STATE FEATURE CODE STATUS LAT (DD MM) LONG (DD MM) ELEVATION (m)
ROCKINGHAM WA LOCB (Towns & Localities) Official -32 16 115 43 -
Australian Geomagnetic Reference Field Computation
Requested: Latitude -32o 16' 00", Longitude 115o 43' 00", Elevation 0 km, Date 2011/01/1
Calculated: Latitude -32.2667o, Longitude +115.7167o, Elevation 0.00 km, Epoch 2011.0000
Magnetic Field Components
D = -1.833 deg
Therefore your accurate, compensated magnetic compass will be pointing about 1.8 deg west of true north. Equally 1.8 deg east of true south. That should be within the azimuth adjustment range of any GEM if you were to start with the mount aligned on magnetic south.
If your tripod is steel or there is any steel fences/reinforcing/tanks/etc nearby, it will affect your compass.
Simply, your compass will show that South is 180 degrees (Magnetic). If you live in Melbourne your magnetic declination is 11.18 degrees to the East. That means your True South on your compass will be 168.82 degrees.
Magnetic Declination Map for Australia
