An apparatus and method for conducting a search of a predetermined area for radiant energy utilizing a raster type scan and responsive to receipt of radiant energy automatically shifting the operational mode from search to track after which that portion of the predetermined area within which the radiant energy was located is repeatedly unidirectionally swept with each succeeding sweep being in quadrature relationship to the previous sweep. A pulse indicative of received radiant energy is produced during each sweep and if of sufficient magnitude, the leading and trailing edges are utilized to cause sampling of deflection currents at the time of occurrence of said leading and trailing edges. The thus sampled currents are averaged to produce an analog output signal indicative of the angular position of the source of the radiant energy within the predetermined area along the particular axis established by the sampled sweep currents. Also provided is a selection circuit whereby a particular source of radiant energy can be selected to the exclusion of other sources within the predetermined area.