Index FM 44-100-2 AIR DEFENSE ARTILLERY REFERENCE HANDBOOK
FINAL DRAFT - 31 March 2000


APPENDIX C

WORLD GEOGRAPHIC REFERENCE SYSTEM

This appendix describes the world Geographic Reference System (GEOREF) and how to convert geographic coordinates to GEOREF. It is a worldwide position reference system that may be applied to any map or chart graduated in latitude and longitude, regardless of projection. GEOREF is used in all joint AD operations. ADA units use GEOREF on EW plotting boards, on radar PPI screens, and to voice-report target positions in AD C2 systems.

GEOGRAPHIC COORDINATES

    1. Geographic coordinates are reported as longitude and latitude. Longitude coordinates are identified as west or east (W or E) of the prime meridian. Latitude coordinates are identified as north or south (N or S) of the equator (figure C-1).

      2. Figure C-1. Geographic coordinates.

    2. To locate a point using geographic coordinates requires two sets of characters, longitude and latitude coordinates. The world GEOREF system requires only one set of characters to locate the same point. The example in Table C-1 shows the written format for geographic coordinates and GEOREF coordinates for El Paso, Texas.

    Table C-1. El Paso Texas Coordinates

    Longitude

    Latitude

    GEOREF

    1060 25’ 44" W

    310 48’ 06" N

    EJPB 3448

    GEOREF COORDINATES

  1. GEOREF coordinates are divided into three divisions called first, second, and third division GEOREF. The longitude element always comes first. Figure C-2 illustrates the division of GEOREF.

    2. Figure C-2. Divisions of GEOREF

  2. The first division of GEOREF divides the surface of the earth into 24 longitudinal zones of l5° each and 12 latitudinal bands of l5° each. Figure C-3 illustrates first division 15° quadrangles indicating the location of El Paso, Texas.

    3. Figure C-3. GEOREF First Division 150 Quadrangles

  3. In the second division, the l5° quadrangle, first division (designated by the first two letters of the GEOREF code), is subdivided into 225 quadrangles formed by 15 longitudinal zones and 15 latitudinal bands each 1° wide (figure C-4).

    4. Figure C-4. GEOREF Second division 1° Quadrangles

  4. In the third division, the l° second division quadrangle is divided into 60 longitudinal zones of 1° east and west; and 60 latitudinal bands of 1° north or south to make 3600 third division (1°) quadrangles. The third division 1° quadrangles are shown in figure C-5.

  5. A simple way of changing coordinates of longitude and latitude into GEOREF coordinates is by the use of the NEWS (north, east, west, south) rule, and the alphanumerical relationship table shown in figure C-6.

Figure C-5. GEOREF Third Division 1O Quadrangles

Figure C-6. Converting Geographic Coordinates to GEOREF