Brunton GeoTransit, Operator'S Manual

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With the small sight toward the object, read azimuth directly where the south end of the nee-
dle points (“
S ” tip). (Fig 6)
See section 4 for detailed explanation of sighting an azimuth.
The Earth is completely surrounded by a magnetic field, and an unobstructed magnetized
object will orient itself with the earth’s magnetic north and south poles. Magnetic declination
(variation) is the difference between true, geographic north (North Pole) and magnetic north
(in northern Canada), with respect to your position. It is important to note magnetic declina-
tion at your position, because magnetic declination varies and fluctuate slowly at different
rates, around the world.
The isogonic chart (Fig 7) shows North America, only. Use the isogonic chart, a current
United States Geological Survey (USGS), Bureau of Land Management (BLM), another
map, or a computer program to determine magnetic declination at your position.
Declination can be east, west or 0°, from your current position. At 0° declination, true north
and magnetic north are aligned.
Example: If magnetic declination at your position is 15° east, then mag-
netic north is 15° east of true, geographic north. Figure 8 displays true
geographic north and magnetic north, as indicated in the legends of
USGS and BLM maps.
Most maps use true north as a reference. When adjustment for magnet-
ic declination is complete, azimuth readings will be with respect to true
north, same as the map.
True North
Magnetic North
15 o E
Your Position
Figure 8
Figure 7
West Declination
East Declination
6 5
Object
Large Sight
“N” Tip
Figure 5
Small Sight
“ S ” Tip
Object
Figure 6
2 -- Magnetic Declination