moffat_psf

artpop.image.moffat_psf(fwhm, pixel_scale=0.2, shape=41, alpha=4.765, mode='center', factor=10)[source]

Moffat point-spread function.

Parameters
fwhmfloat or Quantity

Full width at half maximum of the psf. If a float is given, the units will be assumed to be arcsec. The units can be angular or in pixels.

pixel_scalefloat or Quantity, optional

The pixel scale of the psf image. If a float is given, the units are assumed to be arcsec / pixel (why would you want anything different?).

shapeint or list-like, optional

Shape of the psf image. Must be odd. If an int is given, the x and y dimensions will be set to this value: (shape, shape).

alphafloat, optional

Power index of the Moffat model.

modestr, optional
One of the following discretization modes:
  • ‘center’ (default)

    Discretize model by taking the value at the center of the bin.

  • ‘linear_interp’

    Discretize model by linearly interpolating between the values at the corners of the bin.

  • ‘oversample’

    Discretize model by taking the average on an oversampled grid.

  • ‘integrate’

    Discretize model by integrating the model over the bin. Very slow.

factornumber, optional

Factor of oversampling. Default factor = 10. If the factor is too large, evaluation can be very slow.

Returns
psfndarray

The PSF image normalized such that its sum is equal to one.

Notes

The default value alpha = 4.765 is a fit to the prediction from atmospheric turbulence theory (Trujillo et al. 2001).