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Multipole Map with Healpix routines

  1. Sep 17, 2014 #1
    Hello,

    I have to create the CMB multipole map from a Planck Data Map with Healpix routines on IDL, and I just don't got a clue of how it must be done!

    Can anybody help me?


    Thanks!

    physfed
     
    Last edited: Sep 17, 2014
  2. jcsd
  3. Sep 18, 2014 #2

    Chalnoth

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    First, were you able to properly get Healpix working within IDL? By default, enabling Healpix in IDL changes the IDL> prompt to HIDL>, which should make it obvious if it's working or not.

    Once you have the Healpix routines working, it's a simple matter of executing the mollview command:
    HIDL> mollview <filename>

    The full documentation for the mollview command is here:
    http://healpix.jpl.nasa.gov/html/idlnode33.htm

    Edit: Bah, I misread your question. The power spectrum is a bit more involved. Give me a moment....
     
  4. Sep 18, 2014 #3

    Chalnoth

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    Okay, the power spectrum has to be done with a few different commands. First, you read the FITS file using the read_fits_map (or read_tqu if it's a temperature + polarization map).

    Once you have the Healpix map in memory within IDL, the next step is computing a spherical harmonic transform using the ianafast command (this requires that you have either the F90 or C++ anafast routine installed). Use the cl_out parameter to store the power spectrum, which can then be plotted. Make sure you provide the correct ordering scheme to this routine (the pixel ordering, either RING or NEST, can be read from the FITS header).

    Documentation for all of the IDL commands can be found here:
    http://healpix.jpl.nasa.gov/html/idl.htm
     
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