The 123 mm 8kX3k e2v/Ohio State CCD231-68 for MODS

As is only fitting, the largest Optical/Infrared Telescope (the Large Binocular Telescope, LBT) has the two largest telescope-mounted spectrographs (MODS) and the MODS's have the four largest scientific CCDs. We describe herein the design, fabrication and early use of the e2v CCD231-68 8k × 3k 15 micron back-illuminated detector designed specifically for low and intermediate resolution multi-object spectroscopy on large telescopes. The 123 mm length of the CCD231-68 is the largest of any scientific CCD. The device can be read out in full frame mode to cover the whole 6 arc-min slit length of MODS, in full frame mode for multi-object spectroscopy with short slits, or in split frame transfer mode to allow readout while integrating subsequent exposures. The four very low noise ( - RMS at 100 kPixels/second) outputs are located at the ends of the four 4k serial registers. Excellent CTE (five-9s5 per Pixel) insures good photometric accuracy across the device. Backthinned red and blue optimized variants are used on the corresponding channels of both MODS.