20,437 research outputs found

    Maximum likelihood analysis of systematic errors in interferometric observations of the cosmic microwave background

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    We investigate the impact of instrumental systematic errors in interferometric measurements of the cosmic microwave background (CMB) temperature and polarization power spectra. We simulate interferometric CMB observations to generate mock visibilities and estimate power spectra using the statistically optimal maximum likelihood technique. We define a quadratic error measure to determine allowable levels of systematic error that do not induce power spectrum errors beyond a given tolerance. As an example, in this study we focus on differential pointing errors. The effects of other systematics can be simulated by this pipeline in a straightforward manner. We find that, in order to accurately recover the underlying B-modes for r=0.01 at 28<l<384, Gaussian-distributed pointing errors must be controlled to 0.7^\circ rms for an interferometer with an antenna configuration similar to QUBIC, in agreement with analytical estimates. Only the statistical uncertainty for 28<l<88 would be changed at ~10% level. With the same instrumental configuration, we find the pointing errors would slightly bias the 2-\sigma upper limit of the tensor-to-scalar ratio r by ~10%. We also show that the impact of pointing errors on the TB and EB measurements is negligibly small.Comment: 10 pages, 4 figures, accepted for publication in ApJS. Includes improvements in clarity of presentation and Fig.4 added, in response to refere

    Measuring National Wellbeing

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    A First Map of the CMB at 0.5Deg Resolution

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    We use a Maximum Entropy technique to reconstruct a map of the microwave sky near the star Gamma Ursae Minoris, based on data from flights 2, 3 and 4 of the Millimeter-wave Anisotropy eXperiment (MAX).Comment: 5 pages plus 3 postscript figures, uuencoded compressed postscript, CfPA-94-TH-5

    GOVERNMENT POLICY, WIND EROSION, AND ECONOMIC VIABILITY IN SEMI-ARID AGRICULTURE: THE CASE OF THE SOUTHERN TEXAS HIGH PLAINS

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    The 1996 farm bill challenges agricultural producers to pursue conservation objectives while allowing flexibility and reducing subsidies. The nature of this challenge for semi-arid rainfed, wind-erosion-prone agriculture is explored via a behavioral model. Simulations of farm-firm decision making under scenarios in the southern Texas High Plains are evaluated. Results indicate that the removal of subsidies, while lowering farm incomes, does not, under most assumptions, alter cropping system choice. Alternatively, under a variety of assumptions, the imposition of an erosion tax shuts down cropping.Conservation practices, Cropping system choice, Economic dynamics, FAIR Act of 1996, Agricultural and Food Policy,

    U.S. TOBACCO OUTLOOK

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    Crop Production/Industries,

    Fisher Matrix Optimization of Cosmic Microwave Background Interferometers

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    We describe a method for forecasting errors in interferometric measurements of polarization of the cosmic microwave background (CMB) radiation, based on the use of the Fisher matrix calculated from the visibility covariance and relation matrices. In addition to noise and sample variance, the method can account for many kinds of systematic error by calculating an augmented Fisher matrix, including parameters that characterize the instrument along with the cosmological parameters to be estimated. The method is illustrated with examples of gain errors and errors in polarizer orientation. The augmented Fisher matrix approach is applicable to a much wider range of problems beyond CMB interferometry.Comment: Phys. Rev. D 93, 023512 (2016), v4 has no further change
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