Area correlation tracking is an effective solution for tracking targets that have neither prominent features nor high contrast with the background. We address the implementation of a real-time area correlation tracker (ACT) for an on-board application based on the absolute difference algorithm. The ACT consists of a very high speed and very large scale field programming gate array (FPGA), which contains a special structure of parallel pipelined systolic array to accomplish the correlation computation, and a float-pointed digital signal processor (DSP), which does the parabolic interpolation. The configuration and the timing of the ACT are presented and the ACT is applied successfully in a real-time tracking system. The computation latency for correlation tracking is about 2 ms, which can satisfy the demand of the tracking system used for detecting the solar pore's motion induced by atmospheric turbulence and the mechanical vibrations of the solar telescope. (C) 2003 Society of Photo-Optical Instrumentation Engineers.