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B M O C
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)
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
5156
466
(Northing)
(Easting)
Map
5156
466
5157 5157
467
467
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Determining Coordinates: Easting
465 466
5157
5156
Determine the easting first:From the object on map ( ) go
to the bottom (or top) edge of the map
Find the nearest smaller coordinate to the LEFT (W) of your point
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Determining Coordinates: Easting
4 6 5 0 0 0
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Determining Coordinates: EastingDivide the distance between the coordinate to the left of your point and the coordinate to the right of your point into tenths
465 466
3 tenths This is hundreds of meters
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Determining Coordinates: Easting
4 6 5 3 0 0
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Determining Coordinates: Northing
465 466
5157
5156
From the point on map ( ) look to the left (or right) edge of the map
Find the nearest coordinate below (S) of your point
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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.
465360E
5165820N
Starting corner:465000E 5165000N
Template placed on map at kilometer grid corner
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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
5165820N
Starting corner:465000E 5165000N
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Start here.
489000E, 5315000N
489520E
5315440N
Determining Coordinates
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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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Start here. 490, 5315
5315340N
490120E
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 153N NAD83 : nearest 100 meters
