Abstract: Apparatus and method for collecting magnetometer data at the earth's surface in order to detect anomalies in the earth's magnetic field caused by buried ferromagnetic objects. A plurality of magnetometers are provided in a predetermined array on a mobile platform. A fixed station is also provided on the earth's surface, and navigational data from a global positioning system (GPS) is collected on the locations of the fixed station and mobile platform in synchronization with a sync signal received from the GPS. While the mobile platform traverses an area on the earth's surface, magnetometer data is collected in synchronization with the sync signal. The apparatus and method provide a significant improvement in the amount of area which can be surveyed in a given time period and in the precision of the location and magnetic field intensity data collected.