eastings

Eastings are a coordinate system used in cartography and surveying to specify a location's east-west position. They represent the distance, measured in meters, eastward from a defined meridian, known as the origin meridian or false origin. This origin meridian is a line of longitude chosen for a specific map projection or coordinate system. For example, in the Universal Transverse Mercator (UTM) system, the origin meridian for each zone is its central meridian, and a false easting of 500,000 meters is added to ensure all eastings within a zone are positive. This prevents negative numbers and simplifies calculations.

Eastings are always paired with northings, which represent the north-south position. Together, the easting and northing values form a grid reference that uniquely identifies a point on a map. The accuracy of an easting value depends on the precision of the surveying equipment used and the accuracy of the underlying map projection. Eastings are fundamental to tasks such as land surveying, navigation, and geographic information systems (GIS), allowing for precise measurement and analysis of spatial data. Understanding eastings is crucial for anyone working with maps or geospatial data.