Japanese website DCWatch has published a test of the star tracking feature of Pentax's O-GPS module. The Astro Tracer mode uses the GPS coordinates to calculate the camera's movement relative to the stars, then utilizes the camera's image stabilization system to shift the sensor to track that movement. The report, which is a little tricky to follow in its Google-translated form, includes several example images, showing the system's effectiveness. (From DCWatch)

Click here to read the Google translated version of DCWatch's O-GPS Astro Tracer report