ShellSpatialModel

class gammapy.modeling.models.ShellSpatialModel(lon_0, lat_0, radius, width, frame='icrs')

Bases: gammapy.modeling.models.SpatialModel

Shell model.

\[\begin{split}\phi(lon, lat) = \frac{3}{2 \pi (r_{out}^3 - r_{in}^3)} \cdot \begin{cases} \sqrt{r_{out}^2 - \theta^2} - \sqrt{r_{in}^2 - \theta^2} & \text{for } \theta \lt r_{in} \\ \sqrt{r_{out}^2 - \theta^2} & \text{for } r_{in} \leq \theta \lt r_{out} \\ 0 & \text{for } \theta > r_{out} \end{cases}\end{split}\]

where \(\theta\) is the sky separation and \(r_{\text{out}} = r_{\text{in}}\) + width

Note that the normalization is a small angle approximation, although that approximation is still very good even for 10 deg radius shells.

Parameters:

lon_0, lat_0 : Angle

Center position

radius : Angle

Inner radius, \(r_{in}\)

width : Angle

Shell width

frame : {“icrs”, “galactic”}

Center position coordinate frame

Attributes Summary

evaluation_radius	Evaluation radius (Angle).
frame
lat_0
lon_0
parameters	Parameters (Parameters)
position	Spatial model center position
radius
tag
width

Methods Summary

__call__(self, lon, lat)	Call evaluate method
copy(self)	A deep copy.
create(tag, \*args, \*\*kwargs)	Create a model instance.
evaluate(lon, lat, lon_0, lat_0, radius, width)	Evaluate model.
evaluate_geom(self, geom)	Evaluate model on Geom.
from_dict(data)
to_dict(self)

Attributes Documentation

evaluation_radius

Evaluation radius (Angle).

Set to \(r_\text{out}\).

frame

lat_0

lon_0

parameters

Parameters (Parameters)

position

Spatial model center position

radius

tag = 'ShellSpatialModel'

width

Methods Documentation

__call__(self, lon, lat)

Call evaluate method

copy(self)

A deep copy.

static create(tag, *args, **kwargs)

Create a model instance.

Examples

>>> from gammapy.modeling import Model
>>> spectral_model = Model.create("PowerLaw2SpectralModel", amplitude="1e-10 cm-2 s-1", index=3)
>>> type(spectral_model)
gammapy.modeling.models.spectral.PowerLaw2SpectralModel

static evaluate(lon, lat, lon_0, lat_0, radius, width)

Evaluate model.

evaluate_geom(self, geom)

Evaluate model on Geom.

classmethod from_dict(data)

to_dict(self)