A millimeter wave radiometer is started operation at the Swedish Institute of Space Physics, Kiruna, Sweden. The location of the instrument (67.8 N, 20.4 E) allows continuous observation of the evolution of ozone and ozone related trace gases in the Arctic polar stratosphere. It is designed for measurements of thermal emission lines around 204 Ghz. At this frequency observations include of ozone, chlorine monoxide, nitrous oxide, and nitric acid.