Characterization of a deep-depletion 4K x 4K charge-coupled device detector system designed for ARIES Devasthal faint object spectrograph

We present the characterization of the charge-coupled device (CCD) system developed for the ARIES Devasthal faint object spectrograph (ADFOSC) instrument on the 3.6 m Devasthal optical telescope (DOT). We describe various experiments performed to tune the CCD controller parameters to obtain optimum performance in single and four-port readout modes. Different methodologies employed for characterizing the performance parameters of the CCD, including bias stability, noise, defects, linearity, and gain, are described here. The CCD has grade-0 characteristics at temperatures close to its nominal operating temperature of -120 degrees C. The overall system is linear with a regression coefficient of 0.9999, readout noise of six electrons, and a gain value close to unity. We demonstrate a method to calculate the dark signal using the gradient in the bias frames at lower temperatures. Using the optimized setting, we verify the performance of the CCD detector system on-sky using the ADFOSC instrument mounted on the 3.6 m DOT. Some science targets were observed to evaluate the detector's performance in both imaging and spectroscopic modes. (c) 2023 Society of Photo-Optical Instrumentation Engineers (SPIE)