The German Receiver for Astronomy at Terahertz Frequencies (GREAT) allows observations in the far infrared range. The device (metal-coloured, rectangular structure on the right) was designed and built in Germany. For the instrument to be able to observe in the required infrared range, the sensor must be cooled down. This is done with the aid of liquid nitrogen and helium. Protective clothing must be worn when pouring these ice cold substances to prevent injury.