A measurement of Omega from the North American test flight of Boomerang

We use the angular power spectrum of the cosmic microwave background, measu red during the North American test flight of the Boomerang experiment, to c onstrain 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 less than or equal to Omega less than or e qual to 1.25 at the 68% confidence level. Combined with the COBE measuremen t, the data on degree scales from the Microwave Anisotropy Telescope in Chi le, and the high-redshift supernovae data, we obtain new constraints on the fractional matter density and the cosmological constant.