Average dark signal image at 2-s integration time of the HG image acquired in-flight. The signal is dominated by a four-column repeating pattern due to the column gain multiplexing. The read noise is low due to averaging and the dark current is negligible at operating temperature (–50°C). The stitching line of the detector is visible here as a column with an off-point due to the optimized 2K × 2K centring.