PSFMap¶

class gammapy.cube.PSFMap(psf_map, exposure_map=None)[source]¶

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. exposure_map : `Map` Associated exposure map. Needs to have a consistent map geometry.

Examples

import numpy as np
from astropy import units as u
from astropy.coordinates import SkyCoord
from gammapy.maps import Map, WcsGeom, MapAxis
from gammapy.irf import EnergyDependentMultiGaussPSF, EffectiveAreaTable2D
from gammapy.cube import make_psf_map, PSFMap, make_map_exposure_true_energy

# 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)
aeff2d = EffectiveAreaTable2D.read(filename, hdu='EFFECTIVE AREA')

# Create the exposure map
exposure_geom = geom.to_image().to_cube([energy_axis])
exposure_map = make_map_exposure_true_energy(pointing, "1 h", aeff2d, exposure_geom)

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

# 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')

Methods Summary

`containment_radius_map`(self, energy[, fraction])	Containment radius map.
`from_hdulist`(hdulist[, psf_hdu, …])	Convert to `HDUList`.
`get_energy_dependent_table_psf`(self, position)	Get energy-dependent PSF at a given position.
`get_psf_kernel`(self, position, geom[, …])	Returns a PSF kernel at the given position.
`read`(filename, \\kwargs)	Read a psf_map from file and create a PSFMap object
`stack`(self, other)	Stack PSFMap with another one.
`to_hdulist`(self[, psf_hdu, psf_hdubands, …])	Convert to `HDUList`.
`write`(self, filename[, overwrite])	Write to fits

Methods Documentation

containment_radius_map(self, energy, fraction=0.68)[source]¶

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

classmethod from_hdulist(hdulist, psf_hdu='PSFMAP', psf_hdubands='BANDSPSF', exposure_hdu='EXPMAP', exposure_hdubands='BANDSEXP')[source]¶

Convert to HDUList.

Parameters:	psf_hdu : str Name or index of the HDU with the psf_map data. psf_hdubands : str Name or index of the HDU with the psf_map BANDS table. exposure_hdu : str Name or index of the HDU with the exposure_map data. exposure_hdubands : str Name or index of the HDU with the exposure_map BANDS table.

get_energy_dependent_table_psf(self, position)[source]¶

Get energy-dependent 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(self, position, geom, max_radius=None, factor=4)[source]¶

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)[source]¶: Read a psf_map from file and create a PSFMap object

stack(self, other)[source]¶

Stack PSFMap with another one.

The other PSFMap is projected on the current PSFMap geometry.

Parameters:	other : `PSFMap` the psfmap to be stacked with this one.
Returns:	new : `PSFMap` the stacked psfmap

to_hdulist(self, psf_hdu='PSFMAP', psf_hdubands='BANDSPSF', exposure_hdu='EXPMAP', exposure_hdubands='BANDSEXP')[source]¶

Convert to HDUList.

Parameters:	psf_hdu : str Name or index of the HDU with the psf_map data. psf_hdubands : str Name or index of the HDU with the psf_map BANDS table. exposure_hdu : str Name or index of the HDU with the exposure_map data. exposure_hdubands : str Name or index of the HDU with the exposure_map BANDS table.
Returns:	hdu_list : `HDUList`

write(self, filename, overwrite=False, **kwargs)[source]¶: Write to fits