The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, 1999, Ir Energy Distributions And Imaging Of The 12Um Active Galaxies Towards A Unification Scheme Of Active Galactic Nuclei. Part 2, 1.0, European Space Agency, https://doi.org/10.5270/esa-lrg9hyg