A sun sensor determines a spacecraft’s orientation with respect to the sun. The front surface of the NewSpace Systems (NSS) NFSS-411 sensor is a synthetic sapphire window with a reflective metal coating beneath. Slits are etched in the metal and sunlight passes through them and through an optical filter onto a sensor. The charge on the photo-sensors is read by the microcontroller which processes the image and computes the sun vector. the vector and other telemetry are returned to the spacecraft through the serial interface. The NSS Fine Sun Sensor accepts the configuration commands and outputs digital angles and telemetry over a serial interface to the on-board computer. The unit can be powered from unregulated DC power from the spacecraft.