GPSLongitude

GPSLongitude is the longitude component of a geographic coordinate produced by GPS devices and related systems. It represents the angular distance of a location east or west of the Prime Meridian, measured in degrees.

In decimal-degree form, longitude values typically range from -180 to +180, with positive values indicating east of Greenwich and negative values indicating west. In other representations, longitude may be stored as degrees, minutes, and seconds with a separate direction indicator (E or W).

Longitude is always used together with latitude to specify a position on the Earth's surface. The pair may be expressed in various formats depending on the data source: GPS receivers and mapping software commonly use decimal degrees; traditional NMEA 0183 data uses degrees and minutes plus a direction; EXIF GPS tags or ISO 6709 use formatted strings or compact numeric representations.

Geodetic datum: GPS longitude values are referenced to a geodetic datum, most commonly WGS 84 in GPS outputs, though some applications use local datums that shift coordinates slightly.

Applications and accuracy: longitude data underpin navigation, cartography, geographic information systems, geotagging of photos, and location-based services. Accuracy depends on satellite geometry, atmospheric conditions, multipath, and receiver quality. In high-precision contexts, differential GPS or augmentation systems may improve accuracy.

See also: GPSLatitude, NMEA 0183, EXIF GPS tags, ISO 6709, WGS84.