Measurements of Anisotropy in the Cosmic Microwave Background Radiation at 0[fdg]5 Scales near the Stars HR 5127 and φ Herculis

Abstract

We present measurements of cosmic microwave background (CMB) anisotropy near the stars HR 5127 and Herculis from the fifth flight of the Millimeter-wave Anisotropy eXperiment (MAX). We scanned 8° strips of the sky with an approximately Gaussian 05 FWHM beam and a 14 peak to peak sinusoidal chop. The instrument has four frequency bands centered at 3.5, 6, 9, and 14 cm-1. The IRAS 100 μm map predicts that these two regions have low interstellar dust contrast. The HR 5127 data are consistent with CMB anisotropy. The Herculis data, which were measured at lower flight altitudes, show time variability at 9 and 14 cm-1, which we believe to be due to atmospheric emission. However, the Herculis data at 3.5 and 6 cm-1 are essentially independent of this atmospheric contribution and are consistent with CMB anisotropy. Confusion from Galactic foregrounds is unlikely based on the spectrum and amplitude of the structure at these frequencies. If the observed HR 5127 structure and the atmosphere-independent Herculis structure are attributed to CMB anisotropy, then we find ΔT/T = l(l + 1)Cl/2π1/2 = 1.2+ 0.4−0.3 × 10-5 for HR 5127 and 1.9+ 0.7−0.4 × 10-5 for Herculis in the flat band approximation. The upper and lower limits represent a 68% confidence interval added in quadrature with a 10% calibration uncertainty.