At which North Pole does Santa Claus live?

North Reference

True North The earth’s axis of rotation

Magnetic North Where your compass points

Grid North Where the UTM grid lines “point” to

Grid Nerd

The North Reference you choose

determines where 0° is when you measure an angle

with your protractor or compass.

MN

15°GN

0° 25'

N340320

300

280

W26

024

022

0

200S 160

140

120

100E

8060

40

20

0355350345340335330325320

310

305

300

295

290

285

280

275

270

315

9085

8075

7065

6055

50

403530252015105

180185190195200205210215220

140145150155160165170175

45

130125

120115

110105

10095

135

265

260

255

250

245

240

235

230

225

www.maptools.com©2004 MapTools

0 1 2 3 4 5 6 7 8 90123456789

1:24,000 UTM GridEach mark is 100 meters

MN

15°GN

0° 25'

True v.s. Magnetic North

What is the difference here?

• Fruitvale Ave. is aligned with True North. • So are the edges of parking lots 4 & 5. • Let’s go take a bearing along the edge of lot 4

and see what we get…

USA Declination Map

World Declination Map

High Definition Geomagnetic Model

Declination Diagrams

Declination changes over time

• Here in Northern California it changes by about 1° every 20 years.

• The declination shown on your topo map may be out of date.

• What about declination displayed by my GPS? –It probably correct as of the date of manufacture.

2010

2000

16001700

18001900

2000

19001800 1700 1600

Magnetic Poles

North Pole South Pole

Declination Calculator at www.ngdc.noaa.gov

Local Anomalies

• May be as much as 90 degrees –3-4 degrees is common

• North of Kingston, Ontario; 90° of anomalous declination. • Kingston Harbor, Ontario; 16.3° W to 15.5° E of anomalous declination

over two kilometers (1.2 miles); magnetite and ilmenite deposits. • Savoff, Ontario (50.0 N, 85.0 W). Over 60° of anomalous declination.     • Ramapo Mountains, northeastern New Jersey; iron ore; compass rendered

useless in some areas. • Near Grants, New Mexico north of the Gila Wilderness area; Malpais lava

flows; compass rendered useless.  

MN

14°GN

1° 33'

Using your GPS & compass to measure

current local magnetic declination

d > 300m

WPT001

GPS GOTO WPT001

Bearing 214° True

Compass Bearing to Palm 200° Magnetic

Current Local Magnetic Declination is 14° East of True North

Angular Error in GPS Bearing to Waypoint

10m

x

10m

x

d

α

α

ααd

100m200m300m400m500m600m700m800m900m1000m

6°3°2°

1.4°1.1°1.0°0.8°0.7°0.6°0.57°

tan

tan-1

0 10 20 3040

5060

7080

90100

110120

130

140150160170180190200210

2202

3024025026

027

028

0290300310

320 3

30340 350 MN

16°GN

1° 33'

Using your map & compass to measure

current local magnetic declinationCompass

Trail Jct -> Peak 52° Mag.

From the map Trail Jct -> Peak

68° True

Current local magnetic declination

is (68 - 52) 16° E. of True North

Check you compass & sighting technique using these methods and the declination for the area

• Find some place near your home to establish your personal compass testing location.

• Identify several features, at least 1km away, that you can sight on.

• Use a map to determine True bearings to these features. Convert these bearings to Magnetic using the calculated declination for the area.

• Check your compass and technique. Experiment with the your gear to see if it influences your compass.

• Keep notes, so you can repeat this in the future.