Measurements of anisotropy in the cosmic microwave background radiation at degree angular scales near the stars Sigma Herculis and IOTA Draconis

Abstract

We present results from two four-frequency observations centered near the stars Sigma Herculis and Iota Draconis during the fourth flight of the Millimeter-wave Anisotropy eXperiment (MAX). The observations were made of 6 deg x 0.6 deg strips of the sky with a 1.4 deg peak to peak sinusoidal chop in all bands. The full width at half maximum (FWHM) beam sizes were calculated 0.55 deg +/- 0.05 deg at 3.5/cm and a 0.75 deg +/- 0.05 deg at 6, 9, and 14/cm. Significant correlated structures were observed at 3.5, 6, and 9/cm. The spectra of these signals are inconsistent with thermal emission from known interstellar dust populations. The extrapolated amplitudes of synchrotron and free-free emission are too small to account for the amplitude of the observed structures. If the observed structures are attributed to cosmic microwave background (CMB) anisotropy with a Gaussian autocorrelation function and a coherence angle of 25 min, then the most probable values at Delta T/T<SUB>CMB</SUB> = 3.1 <SUP>+1.7</SUP><SUB>-1.3</SUB>x 10<SUP>-5</SUP> for the Sigma Herculis scan, and Delta T/T<SUB>CMB</SUB> = 3.3<SUP>+1.1</SUP><SUB>-1.1</SUB> x 10<SUP>-5</SUP> for the Iota Draconis scan (95% confidence upper, lower limits).