PSFMap

class gammapy.cube.PSFMap(psf_map)

Bases: object

Class containing the Map of PSFs and allowing to interact with it.

Parameters:

psf_map : Map

the input PSF Map. Should be a Map with 2 non spatial axes. rad and true energy axes should be given in this specific order.

Examples

import numpy as np
from gammapy.maps import Map, WcsGeom, MapAxis
from gammapy.irf import EnergyDependentMultiGaussPSF
from gammapy.cube import make_psf_map, PSFMap
from astropy import units as u
from astropy.coordinates import SkyCoord

# Define energy axis. Note that the name is fixed.
energy_axis = MapAxis.from_edges(np.logspace(-1., 1., 4), unit='TeV', name='energy')
# Define rad axis. Again note the axis name
rads = np.linspace(0., 0.5, 100) * u.deg
rad_axis = MapAxis.from_edges(rads, unit='deg', name='theta')

# Define parameters
pointing = SkyCoord(0., 0., unit='deg')
max_offset = 4 * u.deg

# Create WcsGeom
geom = WcsGeom.create(binsz=0.25*u.deg, width=10*u.deg, skydir=pointing, axes=[rad_axis, energy_axis])

# Extract EnergyDependentTablePSF from CTA 1DC IRF
filename = '$GAMMAPY_DATA/cta-1dc/caldb/data/cta/1dc/bcf/South_z20_50h/irf_file.fits'
psf = EnergyDependentMultiGaussPSF.read(filename, hdu='POINT SPREAD FUNCTION')
psf3d = psf.to_psf3d(rads)

# create the PSFMap for the specified pointing
psf_map = make_psf_map(psf3d, pointing, geom, max_offset)

# Get an EnergyDependentTablePSF at any position in the image
psf_table = psf_map.get_energy_dependent_table_psf(SkyCoord(2., 2.5, unit='deg'))

# Write map to disk
psf_map.write('psf_map.fits')

Attributes Summary

data	the PSFMap data
geom	The PSFMap MapGeom object
psf_map	the PSFMap itself (Map)
quantity	the PSFMap data as a quantity

Methods Summary

containment_radius_map(energy[, fraction])	Containment radius map.
get_energy_dependent_table_psf(position)	Returns EnergyDependentTable PSF at a given position
get_psf_kernel(position, geom[, max_radius, …])	Returns a PSF kernel at the given position.
read(filename, **kwargs)	Read a psf_map from file and create a PSFMap object
write(*args, **kwargs)	Write the Map object containing the PSF Library map.

Attributes Documentation

data

the PSFMap data

geom

The PSFMap MapGeom object

psf_map

the PSFMap itself (Map)

quantity

the PSFMap data as a quantity

Methods Documentation

containment_radius_map(energy, fraction=0.68)

Containment radius map.

Parameters:

energy : Quantity

Scalar energy at which to compute the containment radius

fraction : float

the containment fraction (range: 0 to 1)

Returns:

containment_radius_map : Map

Containment radius map

get_energy_dependent_table_psf(position)

Returns EnergyDependentTable PSF at a given position

Parameters:

position : SkyCoord

the target position. Should be a single coordinates

Returns:

psf_table : EnergyDependentTablePSF

the table PSF

get_psf_kernel(position, geom, max_radius=None, factor=4)

Returns a PSF kernel at the given position.

The PSF is returned in the form a WcsNDMap defined by the input MapGeom.

Parameters:

position : SkyCoord

the target position. Should be a single coordinate

geom : MapGeom

the target geometry to use

max_radius : Angle

maximum angular size of the kernel map

factor : int

oversampling factor to compute the PSF

Returns:

kernel : PSFKernel

the resulting kernel

classmethod read(filename, **kwargs)

Read a psf_map from file and create a PSFMap object

write(*args, **kwargs)

Write the Map object containing the PSF Library map.