 The telescope and its detectors cover a wide wavelength range from the near infrared to the sub-millimeter region; no window material is transparent over this whole range, so the observations are made through a square hole in the port upper quarter of the rear fuselage, aft of a new pressure bulkhead.A sliding door covers the aperture when the telescope is not in use.Astronomers take data and control the instrument from within the normally pressurised cabin.