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.
- fwhmfloat or
- Returns
- psf
ndarray
The PSF image normalized such that its sum is equal to one.
- psf
Notes
The default value
alpha = 4.765
is a fit to the prediction from atmospheric turbulence theory (Trujillo et al. 2001).