The Odin satellite was launched from Svobodny in Eastern Siberia on February 20, 2001, almost 12 years after the idea of the third Swedish scientific satellite was proposed. As the satellite concept developed from a pure astronomy mission into a combined Astronomy/Aeronomy mission so did the instrument complement expand from only a sub-millimetre/millimetre radiometer (SMR). In 1994 Canada joined Sweden, France and Finland in the Odin mission and agreed to provide an Optical Spectrograph and InfraRed Imager System (OSIRIS) that would make aeronomy observations that supplement, and complement, the SMR atmospheric observations.

In this seminar the basic concept of the OSIRIS instrument will be described and some of the observations and results from the first eighteen months on orbit presented. There will be a particular emphasis on the tomographic observations and retrievals that represent a major advance for OSIRIS.