Grid Information


GRIDS

Univeral Transverse Mercator (UTM)
The Earth between latitudes 84° N and 80° S is divided into 60 zones each generally 6° wide in longitude. The Earth is divided into 60 zones. They are number from 1 to 60 proceeding east from the 180th meridian from Greenwich. Washington DC is in grid zone 18S covering a quadrangle from long 72° to 78° W and from lat 32° to 40° N. Each of these quadrangles is further divided into grid squares 100,000 meters on a side. The zone number and the x and y coordinates in meters are used to define a point if the ellipsoid and hemisphere (north or south ) are known.

 

Military Grid Reference System (MGRS)
The Earth between latitudes 84° N and 80° S is divided into 60 zones each generally 6° wide in longitude. The Earth is divided into 60 zones. This is much like the UTM coordinate system. The difference between the two is that the 60 zones are divided every 8° of latitude and forms 6 x 8 grid zones with the exception near the poles. Each 100,000 meter square is assigned a two letter scheme to distinguish it from the neighboring squares. The first letter starts with A in the west and goes higher as the zones move east. This letter corresponds to the first digit in the Easting value of a UTM coordinate. The second letter starts with A in the south and rises as you move north. The second letter in the 100,000 meter square identifier corresponds to the second digit in the Northing value of the UTM coordinate.

 

World Geographic Reference System (GEOREF)
The World Geographic Reference System (GEOREF) is an area-designation method used for interservice reporting for air defense and strategic air operations. It provides a method of expressing position in a form suitable for reporting and plotting and may be applied to any map or chart graduated in latitude and longitude. GEOREF defines the unit geographic area in which a specific point lies. The Earth is divided into quadrangles of longitude and latitude with a systematic code that gives positive identification to each quadrangle. The point of origin is the 180° meridian. It extends eastward 360° back to the 180°. It extends northward 180° to the North Pole.

 

World Geographic Reference System (GEOREF)
In the World Geographic Reference System,there are 4 longitudal zones of 15 degrees width lettered A to Z (omitting I and O). There are 12 bands of latitude of 15 degrees lettered A to M (omitting I). The first letter is that of the longitude and the second letter is the latitude band.

 

World Geographic Reference System (GEOREF)
Each 15 degree quadrangle is sub-divided int 15 one degree zones eastward from the western meridian of the quadrangle, lettered A to Q (omitting I and O). Each 15 degree is divided into one degree band of latitude northward from the southern parallel numbered A to Q (omitting I and O). A one degree quadrangle may be identified by four letters. Salisbury is identified by the letters MKPG.

 

World Geographic Reference System (GEOREF)
Each one degree quadrangle is divided into 60 minutes of longitude numbered eastward from its western meridan and 60 minutes of latitude numbered northward from the southern parallel. A unique reference of a point to an accuracy of one minute in latitude and longitude is given by four letters and four numbers. The first two numbers are longtiude minutes and the last two are latitude minutes. The Salisbury Cathedral as shown below is represented as MKPG1204.

Each one degree quadrangle may be further divided into decimal decimal parts. Four letters and six numerals will define a location to .1 minute; four letters and eight numerals will define a location to .01 minutes.

 

 



Point of Contact: Coordinate Systems Analysis Team
phone (314) 676-9124, DSN 846-9124
coordsys@nga.mil

Document last modified September 15, 2014

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