MoffatPSF

class gunagala.psf.MoffatPSF(model=None, shape=2.5, **kwargs)[source]

Bases: gunagala.psf.FittablePSF, astropy.modeling.functional_models.Moffat2D

Class representing a 2D Moffat profile point spread function.

Used to calculate pixelated version of the PSF and associated parameters useful for point source signal to noise and saturation limit calculations.

Parameters:
FWHM : astropy.units.Quantity

Full Width at Half-Maximum of the PSF in angle on the sky units

shape : float, optional

Shape parameter of the Moffat function, must be > 1, default 2.5

pixel_scale : astropy.units.Quantity, optional

Pixel scale (angle/pixel) to use when calculating pixellated point spread functions or related parameters. Does not need to be set on object creation but must be set before before pixellation function can be used.

Notes

Smaller values of the shape parameter correspond to ‘wingier’ profiles. A value of 4.765 would give the best fit to pure Kolmogorov atmospheric turbulence. When instrumental effects are added a lower value is appropriate. IRAF uses a default of 2.5.

Attributes:
n_pix: astropy.units.Quantity

Effective number of pixels

Attributes Summary

param_names
shape Shape parameter of the Moffat function, see Notes.

Attributes Documentation

param_names = ('amplitude', 'x_0', 'y_0', 'gamma', 'alpha')
shape

Shape parameter of the Moffat function, see Notes.

Returns:
shape : float

Shape parameter value.