at which north pole does santa claus live? · 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150...
TRANSCRIPT
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
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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• The declination shown on your topo map may be out of date.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.