The Cooled Grating Spectrometer 4 (CGS4) was designed and built at the ROE, and was commissioned on UKIRT (link opens in a new window) in 1992. Originally it contained a 58x62 pixel array, but this was upgraded to a 256x256 array in 1995. The array is sensitive to infrared light at wavelengths between 1-5 microns and is cooled to 70 K (-203C) by liquid nitrogen and closed cycle coolers.
CGS4 was highly a successful instrument. It obtained infrared spectra for an extraordinarily wide range of astronomical projects, from measuring the physical and chemical properties of asteroid sruface and of the gas and dust between the star to investigating the nature of the most distance galaxeis and supernovae. It provided data for hundreds of scientific papers, helping to keep the UK at the forefront of near infrared spectroscopy. Most of its functions have now been replaced by UIST which was commissioned on UKIRT in autumn 2002.