CatalogImageEstimator

class gammapy.image.CatalogImageEstimator(reference, emin, emax)

Bases: object

Compute model image for given energy band from a catalog.

Sources are only filled when their center lies within the image boundaries.

Parameters:

reference : SkyImage

Reference sky image.

emin : Quantity

Lower bound of energy range.

emax : Quantity

Upper bound of energy range.

Examples

Here is an example how to compute a flux image from a catalog:

from astropy import units as u from gammapy.image import SkyImage, CatalogImageEstimator from gammapy.catalog import SourceCatalogGammaCat

reference = SkyImage.empty(xref=265, yref=-1.5, nxpix=201,

nypix=201, binsz=0.04)

image_estimator = CatalogImageEstimator(reference=reference,

emin=1 * u.TeV, emax=10 * u.TeV)

catalog = SourceCatalogGammaCat() result = image_estimator.run(catalog) result[‘flux’].show()

Currently the CatalogImageEstimator class does not support to compute model cubes of catalogs. But this can achieved with only a little more of python code:

from astropy import units as u from gammapy.image import CatalogImageEstimator, SkyImage from gammapy.cube import SkyCube from gammapy.catalog import SourceCatalogGammaCat from gammapy.utils.energy import EnergyBounds

reference = SkyImage.empty(xref=265, yref=-1.5, nxpix=201,

nypix=201, binsz=0.04)

energies = EnergyBounds.equal_log_spacing(1 * u.TeV, 100 * u.TeV, 3)

flux_cube = SkyCube.empty_like(reference=reference, energies=energies)

catalog = SourceCatalogGammaCat()

for idx in range(energies.size - 1):

image_estimator = CatalogImageEstimator(reference=reference,

emin=energies[idx], emax=energies[idx + 1])

result = image_estimator.run(catalog) flux_cube.data[idx, :, :] = result[‘flux’].data

flux_cube.show()

Methods Summary

flux(catalog)	Compute flux image from catalog.
run(catalog[, which])	Run catalog image estimator.

Methods Documentation

flux(catalog)

Compute flux image from catalog.

Sources are only filled when their center lies within the image boundaries.

Parameters:

catalog : SourceCatalog

Source catalog instance.

Returns:

image : SkyImage

Flux sky image.

run(catalog, which='flux')

Run catalog image estimator.

Parameters:

catalog : SourceCatalog

Source catalog instance.

Returns:

sky_images : SkyImageList

List of sky images