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Pseudo-Isothermal Elliptical Mass Distribution (PIEMD)

:::info Migrated from Old Wiki This content was partially migrated from the old wiki using GitHub Copilot and should be double-checked for accuracy. :::

Usage​

piemd  
  x1c       # x-coordinate of centroid  
  x2c       # y-coordinate of centroid  
  q         # axis ratio (minor/major)  
  pa        # position angle (in radians; counter-clockwise from +x)  
  amp       # amplitude (normalisation; analogous to theta_E in mass PIEMD)  
  w         # core radius

This is the same functional form as the PIEMD mass profile, but used for modelling light.
It is typically employed to describe the stellar light distribution assuming a constant mass-to-light ratio.

Important: The scale: keyword has no effect on the amplitude (unlike in the mass PIEMD profile).