The STAR250 sensor is a CMOS Active Pixel Sensor, designed for application in Optical Inter-Satellite Link beam trackers. The STAR250 is part of broader range of applications including space-borne systems such as sun sensing and star tracking. It features 512 by 512 pixels on a 25 m pitch, on chip Fixed Pattern Noise (FPN) correction, a programmable gain amplifier, and a 10-bit ADC. Flexible operating (multiple windowing, subsampling) is possible by direct addressable X and Y registers.