Anisotropy on Angular Scales of 10 ′ to 5 ◦

We present a map and an angular power spectrum of the anisotropy of the cosmic microwave background (CMB) from the first flight of MAXIMA. MAXIMA is a balloon-borne experiment with an array of 16 bolometric photometers operated at 100 mK. MAXIMA observed a 124 deg region of the sky with 10 resolution at frequencies of 150, 240 and 410 GHz. The data were calibrated using in-flight measurements of the CMB dipole anisotropy. The 410 GHz data were used to place upper limits on atmospheric and galactic dust emission. A map of the CMB anisotropy was produced from three 150 and one 240 GHz photometer without need for foreground subtractions. Analysis of this CMB map yields a power spectrum for the CMB anisotropy over the range 36 ≤ l ≤ 785. The spectrum shows a peak with an amplitude of 78± 6 μK at l ≃ 220 and an amplitude varying between ∼ 40 μK and ∼ 50 μK for 400 . l . 785. Subject headings: cosmic microwave background cosmology: observations