46 research outputs found
A Measurement of the Angular Power Spectrum of the CMB from l = 100 to 400
We report on a measurement of the angular spectrum of the CMB between
and made at 144 GHz from Cerro Toco in the
Chilean altiplano. When the new data are combined with previous data at 30 and
40 GHz, taken with the same instrument observing the same section of sky, we
find: 1) a rise in the angular spectrum to a maximum with K at and a fall at , thereby localizing the peak
near ; and 2) that the anisotropy at has the
spectrum of the CMB.Comment: 4 pages, 2 figures. Revised version; includes Ned Wright's postscript
fix. Accepted by ApJL. Website at http://physics.princeton.edu/~cmb
New CMB Power Spectrum Constraints from MSAMI
We present new cosmic microwave background (CMB) anisotropy results from the
combined analysis of the three flights of the first Medium Scale Anisotropy
Measurement (MSAM1). This balloon-borne bolometric instrument measured about 10
square degrees of sky at half-degree resolution in 4 frequency bands from 5.2
icm to 20 icm with a high signal-to-noise ratio. Here we present an overview of
our analysis methods, compare the results from the three flights, derive new
constraints on the CMB power spectrum from the combined data and reduce the
data to total-power Wiener-filtered maps of the CMB. A key feature of this new
analysis is a determination of the amplitude of CMB fluctuations at . The analysis technique is described in a companion paper by Knox.Comment: 9 pages, 6 included figure
MSAM1-94: repeated measurement of medium-scale anisotropy in the cosmic microwave background radiation
The second flight of the Medium Scale Anisotropy Measurement (MSAM1-94) observed the same field as the first flight (MSAM1-92) to confirm our earlier measurement of cosmic microwave background radiation (CMBR) anisotropy. This instrument chops a 30\arcmin\ beam in a 3 position pattern with a throw of \pm40\arcmin, and simultaneously measures single and double differenced sky signals. We observe in four spectral channels centered at 5.6, 9.0, 16.5, and 22.5~\icm, providing sensitivity to the peak of the CMBR and to thermal emission from interstellar dust. The dust component correlates well with the \IRAS\ 100~\micron\ map. The CMBR observations in our double difference channel correlate well with the earlier observations, but the single difference channel shows some discrepancies. We obtain a detection of fluctuations in the MSAM1-94 dataset that match CMBR in our spectral bands of \Delta T/T = 1.9^{+1.3}_{-0.7}\times 10^{-5} (90\% confidence interval, including calibration uncertainty) for total rms Gaussian fluctuations with correlation angle 0\fdg3, using the double difference demodulation
A Measurement of the Medium-Scale Anisotropy in the Cosmic Microwave Background Radiation
Observations from the first flight of the Medium Scale Anisotropy Measurement
(MSAM) are analyzed to place limits on Gaussian fluctuations in the Cosmic
Microwave Background Radiation (CMBR). This instrument chops a 30\arcmin\ beam
in a 3 position pattern with a throw of \pm40\arcmin; the resulting data is
analyzed in statistically independent single and double difference datasets. We
observe in four spectral channels at 5.6, 9.0, 16.5, and 22.5~\icm, allowing
the separation of interstellar dust emission from CMBR fluctuations. The dust
component is correlated with the \IRAS\ 100~\micron\ map. The CMBR component
has two regions where the signature of an unresolved source is seen. Rejecting
these two source regions, we obtain a detection of fluctuations which match
CMBR in our spectral bands of (90\% CL interval) for total rms Gaussian fluctuations with
correlation angle 0\fdg5, using the single difference demodulation. For the
double difference demodulation, the result is (90\% CL interval) at a correlation angle of 0\fdg3.Comment: 13 pages + 3 figures (included), LaTeX + AASTeX v3.