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Development and characterization of the CCD detector for the Colorado Ultraviolet Transit Experiment (CUTE) cubesat

The Colorado Ultraviolet Transit Experiment (CUTE) is a 6U cubesat housing a Cassegrain telescope and a nea rultraviolet (NUV) spectrograph designed to study the composition and mass-loss rates of exoplanet atmospheres. This instrument covers a bandpass of 250 - 330 nm with a peak effective area of ~28 cm2 and a resolving power of ~2000. The instrument focal plane consists of a back illuminated CCD driven by clocking and readout electronics developed at the Laboratory for Atmospheric and Space Physics (LASP). Special consideration is given to achieving low noise readout due to typical observation signal levels and time constraints of exoplanet transit observations. Additionally, the electronics driving the CCD are space constrained and designed to fit in a cubesat 1/2U volume. Prior to installation in the flight instrument the detector system parameters are optimized and characterized at LASP in a custom ultraviolet detector test chamber. Engineering and technical details including system gain, quantum efficiency, and read noise are discussed. We present the development, optimization, and characterization results of the CCD and associated readout electronics developed for the CUTE instrument.