HEALPix in Megapixels

cosmology
healpy
Published

May 20, 2024

How many megapixels is a HEALPix map?

!pip install healpy
Collecting healpy
  Downloading healpy-1.16.6-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (24.5 MB)
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Requirement already satisfied: matplotlib in /usr/local/lib/python3.10/dist-packages (from healpy) (3.7.1)
Requirement already satisfied: numpy>=1.19 in /usr/local/lib/python3.10/dist-packages (from healpy) (1.25.2)
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Requirement already satisfied: contourpy>=1.0.1 in /usr/local/lib/python3.10/dist-packages (from matplotlib->healpy) (1.2.1)
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Requirement already satisfied: fonttools>=4.22.0 in /usr/local/lib/python3.10/dist-packages (from matplotlib->healpy) (4.51.0)
Requirement already satisfied: kiwisolver>=1.0.1 in /usr/local/lib/python3.10/dist-packages (from matplotlib->healpy) (1.4.5)
Requirement already satisfied: pillow>=6.2.0 in /usr/local/lib/python3.10/dist-packages (from matplotlib->healpy) (9.4.0)
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Requirement already satisfied: six>=1.5 in /usr/local/lib/python3.10/dist-packages (from python-dateutil>=2.7->matplotlib->healpy) (1.16.0)
Installing collected packages: healpy
Successfully installed healpy-1.16.6
import healpy as hp
megapixels = []
for nside_power in range(8, 15):
  nside = 2**nside_power
  megapixels.append((nside, hp.nside2npix(nside)/1e6))
megapixels
[(256, 0.786432),
 (512, 3.145728),
 (1024, 12.582912),
 (2048, 50.331648),
 (4096, 201.326592),
 (8192, 805.306368),
 (16384, 3221.225472)]