Measurement of a Peak in the Cosmic Microwave Background Power Spectrum from the North American Test Flight of Boomerang

We describe a measurement of the angular power spectrum of anisotropies in the cosmic microwave background (CMB) at scales of 0.3d to 5° from the North American test flight of the Boomerang experiment. Boomerang is a balloon-borne telescope with a bolometric receiver designed to map CMB anisotropies on a long-duration balloon flight. During a 6 hr test flight of a prototype system in 1997, we mapped more than 200 deg2 at high Galactic latitudes in two bands centered at 90 and 150 GHz with a resolution of 26' and 16.5′ FWHM, respectively. Analysis of the maps gives a power spectrum with a peak at angular scales of 1° with an amplitude 70 μKCMB.