Archeops

Archeops was a balloon-based submillimeter telescope flown several times between 1999 and 2000. Frequency passbands were 143, 217, 353, and 545 GHz, the former two to observe the cosmic microwave background (CMB) and the latter two to help map the unwanted foreground emissions. Its angular resolution was roughly 15 arcminutes. Its total time of observation was about 19 hours, covering perhaps a quarter to a third of the sky.