The BRITE space telescope: Using a nanosatellite constellation to measure stellar variability in the most luminous stars

The BRIght Target Explorer (BRITE)-Constellation is a group of Canadian/Austrian nanosatellites that will examine the apparently brightest stars in the sky for variability using precise differential photometry. The constellation consists of four low Earth-orbiting nanosatellites, divided into pairs, with each member of a pair having a different optical filter. Each BRITE satellite will observe a region of interest for up to 100 days or longer, allowing the measurement of stellar oscillations on the order of hours to months. Each BRITE satellite utilizes a number of new, innovative technologies including reaction wheels, star tracker and optical telescope, all sized and designed around space flight laboratory's 5-kg, 20×20×20cm3 CanX nanosatellite bus. The BRITE science instrument is a low power complementary metal oxide semiconductor (CMOS) detector coupled with a custom lens system designed to provide a telecentric, slightly defocused image optimized for observing stellar intensity with an accuracy of 1 mmag per data point per orbit down to a visual magnitude of +3.5. Photometric measurements will have an error amplitude spectrum no greater than 20 ppm over measurement periods longer than a month. The optics will have a small (30 mm) aperture and a maximum length of 100 mm in order to fit within the nanosatellite bus.