healpy
37 posts — page 3
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White noise NET in radio-astronomy and cosmology
Create a white noise map and compare with power spectrum expected from the NET
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Planck CMB map at high resolution
Prompted by a colleague, I created a high-resolution version of the Cosmic Microwave Background map in MollWeide projection released by the Planck collaboration, available on the Planck Data Release Website in FITS format.
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Interactive figures in the browser - CMB power spectra
For a long time I've been curious about trying out d3.js , the javascript plotting library which is becoming the standard for interactive plotting in the browser.
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Planck CTP angular power spectrum ell binning
Planck released a binning of the angular power spectrum in the Explanatory supplement, unfortunately the file is in PDF format, non easily machine-readable: http://www.sciops.esa.int/wikiSI/planckpla/index.php?title=Frequencymapsangularpowerspectra&instance=PlanckPublicPLA So here is a csv version: https://gist.github.com/zonca/6288439 Follows embedded gist.
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HEALPix map of the Earth using healpy
HEALPix maps can also be used to create equal-area pixelized maps of the Earth, RGB colors are not supported in healpy, so we need to convert the image to colorscale. The best user case is for using spherical harmonic transforms, e.g. apply a smoothing filter, in this case HEALPix/healpy tools are really efficient.
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Noise in spectra and map domain
Spectra NET or $\sigma$ is the standard deviation of the noise, measured in mK/sqrt(Hz), typical values for microwave amplifiers are 0.2-5. This is the natural unit of the amplitude spectra (ASD), therefore the high frequency tail of the ASD should get to the expected value of the NET.
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Ubuntu PPA for HEALPix and healpy
HEALPix C, C++ version 3.00 and healpy version 1.4.1 are now available in a PPA repository for Ubuntu 12.04 Precise and Ubuntu 12.10 Quantal.