The BRITE Constellation Space Telescope Design and Test of a Wide Field, High Resolution, Low Noise Optical Telescope for a Nanosatellite Constellation

The BRIght Target Explorer (BRITE) Constellation is a nanosatellite-based astro nomy mission tasked with measuring stellar variability of the brightest and most massive stars in the Earth’s sky. Charged with the task of capturing the stellar cycles through photometry, th e payload of the BRITE nanosatellite is a wide-fiel d, high resolution, low noise CCD-based refracting telescop e capable of observing stars with apparent magnitud e of +3.5 and brighter with a signal to noise of 3,000 per 1, 000s cumulative exposure. A number of payload syste m d sign aspects of particular interest to the small satelli te community are discussed including a low-noise CC D-driver design that respects the power limitations of a nanosatell ite, a primarily passive thermal control strategy f or stabilizing the CCD temperature, a software architecture that maxim izes scientific output by enabling highly flexible y t automated payload operations, and a modular mechanical design that ensures maximum flexibility during assembly, focusing, and debugging. In addition, this paper discusses ke y aspects of instrument integration and testing inc luding the focusing process and the challenges associated with achieving acceptable Point Spread Functions in a w ide-field scientific instrument over the entire field of view , imager characterization of bias, gain, saturation level, dark current, and readout noise over temperature.