Last modified: December 2020

URL: https://cxc.cfa.harvard.edu/sherpa/ahelp/devaucouleurs2d.html
AHELP for CIAO 4.13 Sherpa v1

devaucouleurs2d

Context: models

Synopsis

Two-dimensional de Vaucouleurs model.

Syntax

devaucouleurs2d

Description

A spatial de Vaucouleurs profile which is a formulation of the R^(1/4) law introduced by [1] . It is a special case of the sersic2d model with n=4 , as described in [2] , [3] , and [4] .


Example

>>> create_model_component("devaucouleurs2d", "mdl")
>>> print(mdl)

Create a component of the devaucouleurs2d model and display its default parameters. The output is:

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.r0       thawed           10            0  3.40282e+38           
   mdl.xpos     thawed            0 -3.40282e+38  3.40282e+38           
   mdl.ypos     thawed            0 -3.40282e+38  3.40282e+38           
   mdl.ellip    thawed            0            0        0.999           
   mdl.theta    thawed            0     -6.28319      6.28319    radians
   mdl.ampl     thawed            1 -3.40282e+38  3.40282e+38           

ATTRIBUTES

The attributes for this object are:

Attribute Definition
r0 The core radius.
xpos The center of the model on the x0 axis.
ypos The center of the model on the x1 axis.
ellip The ellipticity of the model.
theta The angle of the major axis. It is in radians, measured counter-clockwise from the X0 axis (i.e. the line X1=0).
ampl The amplitude refers to the maximum peak of the model.

Notes

The model used is the same as the sersic2d model with n=4 .

References


Bugs

See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

models
beta2d, hubblereynolds, lorentz2d, sersic2d