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

B M O C Objectives  Understanding UTM system  Finding coordinates of a point  Plotting a point

B M O C 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.

B M O C

 Some USGS sheets have the grid drawn  Older Sheets show blue tick marks and numbers on the border.  Other maps have various ways to show the grid.  Usually written like exponents  Margin numbers are whole kilometers north of equator and east of the zone meridian. Identifying the grid

B M O C Identifying the grid (Northing) (Easting) Map

B M O C Determining Coordinates: Easting 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

B M O C Determining Coordinates: Easting

B M O C 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 tenths This is hundreds of meters

B M O C Determining Coordinates: Easting

B M O C Determining Coordinates: Northing From the point on map ( ) look to the left (or right) edge of the map Find the nearest coordinate below (S) of your point

B M O C Determining Coordinates: Northing

B M O C Determining Coordinates: Northing Count or estimate the number of tenths from the coordinate BELOW your point TO the corner Tenths This is hundreds of meters 51 56

B M O C Determining Coordinates: Northing

B M O C Final Coordinates of E N But we can go finer, if we use a template

B M O C 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 E N Starting corner: E N Template placed on map at kilometer grid corner

B M O C 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 E N Starting corner: E N

B M O C Start here E, N E N Determining Coordinates

B M O C Practice Exercises

B M O C Plotting Points  Underline the last 3 digits of each coordinate.  What’s not underlined are the margin coordinates. Example: E N Use template to determine position within the kilometer box.

B M O C Start here. 490, N E Plotting E N

B M O C Practice Exercises

B M O C 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.

B M O C Example in UTM: 11T E N 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