Method and passive target data acquisition system operable continuously from an observation point for passively sighting a target and acquiring the target on a DTM for passively deriving target data and associated information without emitting radiations prone to detection. The location of the target is shown on a display, and so is an error-area due to measurement inaccuracies. When terrain topography causes the system to indicate more than one error-area, the target and the accompanying error-areas are displayed. The distance between error-areas indicates dead terrain zones. A north finding procedure provides accurate north direction correction to rough north readings taken with a coarse north-indicating device. The system is small enough for integration with handheld personal binoculars, and is operable from static and mobile observation points, possibly on a stabilized platform, on land, at sea, in the air, and in space.