USING UTM, MGRS & USNG
Monica Spicker
Some slides adapted from Harry Frank
2008
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Objectives
Understanding UTM system
Finding coordinates of a
point
Plotting a point
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Universal Transverse Mercator (UTM)
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NATO system
Metric units (meters)
World is split into 60, 6º degree zones
Spokane area is Zone 11N
Distorted above North 84º, and South 80º,
not applied above these latitudes.
Smallest grid unit on USGS 1:24000 maps
is 1 km. May be different on different scale
maps!
Coordinates get larger going east
(easting) from the zone meridian and
larger going north (northing) from the
equator.
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Identifying the grid
466
467
5157
(Easting)
5157
Map
5156
5156
(Northing)
466
467
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Determining Coordinates: Easting
the easting
first: to the
Find theDetermine
nearest smaller
coordinate
FromLEFT
the object
map
( ) go
(W) ofon
your
point
to the bottom (or top) edge of the map
5157
5156
465
466
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Determining Coordinates: Easting
4
6
5
0
0
0
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Determining Coordinates: Easting
Divide the distance between the coordinate to
the left of your point and the coordinate to the right of
your point into tenths
3 tenths
465
This is hundreds of meters
466
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Determining Coordinates: Easting
4
6
5
3
0
0
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Determining Coordinates: Northing
Find
From
the the
nearest
pointcoordinate
on map ( below
) look(S)
to the
of your
left point
(or right) edge of the map
5157
5156
465
466
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Determining Coordinates: Northing
5
1
5
6
0
0
0
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Determining Coordinates: Northing
Count or estimate the number of tenths from the
coordinate BELOW your point TO the corner.
5157
8 Tenths
This is hundreds of meters
5156
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Determining Coordinates: Northing
5
1
5
6
8
0
0
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Final Coordinates of
465300E 5165800N
But we can go finer, if we use a template
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Using a Template
Must match map scale!
Can estimate how far into box on a scale of 1
to 10 to find nearest ten meters.
5165820N
Starting corner:
465000E 5165000N
Template placed
on map at
kilometer grid
corner
465360E
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Another Way to Use the Template
 Put the 0 corner of the template on the point.
 Read where the block margin hits the template scales.
465360E
Starting corner:
465000E 5165000N
5165820N
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Determining Coordinates
489520E
5315440N
Start here.
489000E, 5315000N
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Practice Exercises
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Plotting Points
 Underline the last 3 digits of each coordinate.
 What’s not underlined are the margin
coordinates.
Example: 490150E 5315325N
Use template to determine
position within the kilometer
box.
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490120E
5315340N
Start here. 490, 5315
Plotting 490120E 5315340N
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Practice Exercises
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MGRS and USNG
 Military Grid Reference System
 US National Grid System
 USNG and MGRS are identical
 Based on UTM
 Default datum is NAD83
 Includes
 UTM zone (number and letter)
 A two letter grid designator that replaces the
smaller written UTM number in the margin
 only the ending 5 numbers. More can be
truncated, if you are not going down to single
meters.
 Most GPS support MGRS.
 Most commercial maps do NOT.
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Example
in UTM: 11T 490150E
5315325N
in MGRS:
11T MP 90150E 15325N NAD83 : 1 meter
11T MP 9015E 1532N NAD83
: nearest 10 meters
11T MP 901E
: nearest 100 meters
153N NAD83
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