Measurements of the cosmic microwave background anisotropies with ARCHEOPS

ARCHEOPS is a balloon-borne instrument dedicated to measure cosmic microwave background (CMB) temperature anisotropies at high angular resolution (about 10 ^') over a large fraction (30%) of the sky in the (sub)millimetre domain (from 143 to 545 GHz). Here, we describe the latest results from the instrument during the last flight that happened during the Arctic night from Kiruna (Sweden) to Russia in February 2002. Various sources of noise are discussed, including atmospheric noise, parasitic noise, photon noise, cosmic variance,... The white noise sensitivity for the eight best bolometers is below 200 μK _CMB s ^1/2 per bolometer. Best estimates of the angular power spectrum of the CMB anisotropies are presented, giving for the first time a continuous link between COBE scales and the first acoustic peak. The consequences in terms of cosmological parameters are outlined that reinforce the flatness of the Universe. Other results include the first measurement of polarization and accurate maps of the galactic plane diffuse (sub)millimetre emission.