B M O C USING UTM, MGRS & USNG Monica Spicker Some slides adapted from Harry Frank 2008.

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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