Abstract
Most GPS receivers calculate their locations by a geodetic coordinate referenced to the WGS84 ellipsoid, whereas the local reference applied in IRAQ (referred as ClarkelSSO ellipsoid) have different geodetic coordinates. This paper presents the results of particulars conversion between geographical and UTM grid coordinates system from WGS84 reference ellipsoid system to ClarkelSSO reference ellipsoid system for a selective locations in Mosul (Zone 38N). Conversion formulae and parameters are also given to facilitate users to convert the coordinates of any point in the study area between the two systems by using GPS.receiver and ArcGIS software. The result shows that the geographical and UTM grid systems of the two systems are slightly different, but additive constants are sufficient to attain the general accuracy.
