We use the angular power spectrum of the Cosmic Microwave Background , measured during the North American test flight of the Boomerang experiment , to constrain the geometry of the universe .
Within the class of Cold Dark Matter models , we find that the overall fractional energy density of the universe , \Omega , is constrained to be 0.85 \leq \Omega \leq 1.25 at the 68 \% confidence level .
Combined with the COBE measurement and the high redshift supernovae data we obtain new constraints on the fractional matter density and the cosmological constant .