Smoothing and coordinate transformation¶

Smoothing and coordinate transforms are combined because they are both performed in spherical harmonics space, so we can have a single transform to and from $$a_{lm}$$.

Currently they are implemented as an indepent function pysm.apply_smoothing_and_coord_transform which takes an input map and returns another map either smoothed or coordinate-transformed or both. Usually it operates on maps created with pysm.Sky.get_emission but it would work even with other inputs.

[2]:
sky = pysm.Sky(nside=128, preset_strings=["d1", "s1"])
[3]:
map_100GHz = sky.get_emission(100 * u.GHz)
[4]:
def plot_map(m):
"""Utility function to plot Mollweide view of a map"""
hp.mollview(m[0], min=0, max=1e2, title="I map", unit=m.unit)
[5]:
map_100GHz_smoothed = pysm.apply_smoothing_and_coord_transform(map_100GHz, fwhm=2*u.deg)
plot_map(map_100GHz_smoothed)
[6]:
map_100GHz_rotated = pysm.apply_smoothing_and_coord_transform(map_100GHz, rot=hp.Rotator(coord="GE"))
plot_map(map_100GHz_rotated)
[7]:
map_100GHz_smoothed_rotated = pysm.apply_smoothing_and_coord_transform(map_100GHz, rot=hp.Rotator(coord="GE"), fwhm=2*u.deg)
plot_map(map_100GHz_smoothed_rotated)
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