.. _book_fig_chapter1_fig_healpix_ex:


Example of HealPix pixellization
--------------------------------
Figure 1.15.

The top panel shows HEALPix pixels in nested order. The 12 fundamental sky
divisions can be seen, as well as the hierarchical nature of the smaller
pixels. This shows a pixelization with nside = 4, that is, each of the 12
large regions has 4 x 4 pixels, for a total of 192 pixels. The lower panel
shows a seven-year co-add of raw WMAP data, plotted using the HEALPix
projection using the HealPy package. This particular realization has
nside = 512, for a total of 3,145,728 pixels. The pixels are roughly
6.8 arcminutes on a side.



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.. image:: ../images/chapter1/fig_healpix_ex_1.png
    :align: center
    :scale: 100



.. image:: ../images/chapter1/fig_healpix_ex_2.png
    :align: center
    :scale: 100



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**Python source code:**

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