Showing papers by "Edward J. Wollack published in 1997"
TL;DR: In this paper, the angular power spectrum of the anisotropy in the cosmic microwave background (CMB) was measured in 23 different multipole bands from l = 54 (≈ 3°) to l = 404 ( ≥ 045) and in six frequency bands from 26 to 46 GHz over three observing seasons.
Abstract: We report on a measurement of the angular power spectrum of the anisotropy in the cosmic microwave background (CMB). The anisotropy is measured in 23 different multipole bands from l = 54 (≈ 3°) to l = 404 (≈ 045) and in six frequency bands from 26 to 46 GHz over three observing seasons. The measurements are consistent from year to year. The frequency spectral index of the fluctuations (measured at low l) is consistent with that of the CMB and inconsistent with either dust or Galactic free-free emission. Furthermore, the observations of the MSAM1-92 experiment (Cheng et al. 1994) are repeated and confirmed. The angular spectrum shows a distinct rise from δTl ≡ [l(2l+1)| aml |2/4π]1/2=49+ 8−5 μK at l = 87 to δTl=85+ 10−8 μK at l = 237. These values do not include an overall ±14% (1 σ) calibration uncertainty. The analysis and possible systematic errors are discussed.
201 citations
TL;DR: In this paper, the authors cross-correlate the Saskatoon Ka- and Q-band cosmic microwave background (CMB) data with different maps to quantify possible foreground contamination, and find no significant correlation with point sources, with the Haslam 408 MHz map, or with the Reich and Reich 1420 MHz map.
Abstract: We cross-correlate the Saskatoon Ka- and Q-band cosmic microwave background (CMB) data with different maps to quantify possible foreground contamination. We detect a marginal correlation (2 σ) with the Diffuse Infrared Background Experiment (DIRBE) 240, 140, and 100 μm maps, but we find no significant correlation with point sources, with the Haslam 408 MHz map, or with the Reich and Reich 1420 MHz map. The rms amplitude of the component correlated with DIRBE is about 20% of the CMB signal. Interpreting this component as free-free emission, this normalization agrees with that of the 1996 works of Kogut et al. and supports the hypothesis that the spatial correlation between dust and warm ionized gas observed on large angular scales persists to smaller angular scales. Subtracting this contribution from the CMB data reduces the normalization of the Saskatoon power spectrum by only a few percent.
166 citations
TL;DR: In this paper, an off-axis microwave telescope for observations of the anisotropy in the cosmic microwave background (CMB) radiation on angular scales between 05 and 3° is described.
Abstract: We describe an off-axis microwave telescope for observations of the anisotropy in the cosmic microwave background (CMB) radiation on angular scales between 05 and 3°. The receiver utilizes cryogenic high electron mobility transistor (HEMT) amplifiers and detects the total power in multiple 3 GHz wide channels. Both frequency and polarization information are recorded allowing discrimination between CMB radiation and potential foreground sources and allowing checks for systematic effects. The instrumental radiometric offset is small (~1 mK). Data are taken by rapidly sampling while sweeping the beam many beamwidths across the sky. After detection, a spatio-temporal filter is formed in software that optimizes the sensitivity in a multipole band in the presence of atmospheric fluctuations. Observations were made from Saskatoon, Saskatchewan (SK), Canada, during the winter of 1993 with six channels between 27.6 and 34.0 GHz, in 1994 with 12 channels between 27.6 and 44.1 GHz, and in 1995 with six channels between 38.2 and 44.1 GHz. The performance of the instrument and assessment of the atmospheric noise at this site are discussed.
62 citations
TL;DR: In this article, a Wiener-filtered map of the cosmic microwave background (CMB) fluctuations in a cap with 15° diameter, centered at the north celestial pole, is presented.
Abstract: We present a Wiener-filtered map of the cosmic microwave background (CMB) fluctuations in a cap with 15° diameter, centered at the north celestial pole. The map is based on the 1993-1995 data from the Saskatoon (SK) experiment, with an angular resolution around 1° in the frequency range 27.6-44.1 GHz. The signal-to-noise ratio in the map is of order 2, and some individual hot and cold spots are significant at the 5 σ level. The spatial features are found to be consistent from year to year, which reinforces the conclusion that the SK results are not dominated by residual atmospheric contamination or other noncelestial signals.
42 citations
08 Jun 1997
TL;DR: In this paper, the design, construction and performance of 65-90 GHz and 75-110 GHz low-noise cryogenically-coolable amplifiers are presented, and a comparison between modeled and measured performance is shown.
Abstract: The design, construction and performance of 65-90 GHz and 75-110 GHz low-noise cryogenically-coolable amplifiers are presented. A comparison between modeled and measured performance is shown. A laboratory receiver exhibiting an average noise of 50 K across 65-90 GHz and 70 K across 75-110 GHz is described. These are the widest band and lowest noise HEMT receivers ever reported at these frequencies.
20 citations
07 Jul 1997
TL;DR: In this article, the development of ultra-low-noise, heterostructure field effect transistor (HFET) receivers for frequencies up to 110 GHz is reviewed and applications to radio astronomy receivers, as well as broadband continuum radiometers are discussed.
Abstract: Developments in ultra-low-noise, heterostructure field-effect transistor (HFETs) receivers for frequencies up to 110 GHz are reviewed. Design and examples of the realization of InP HFET receivers in the frequency range 26 to 110 GHz are described. Applications to ultra-low-noise radio astronomy receivers, as well as broadband continuum radiometers, are discussed.
4 citations