PSF

class gunagala.psf.PSF[source]

Bases: object

Abstract base class representing a 2D 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.

Attributes Summary

n_pix The PSF’s effective number of pixels for the worse case where the PSF is centred on the corner of a pixel.
peak The maximum fraction of the total signal that can fall in a single pixel.
pixel_scale Pixel scale used when calculating pixellated point spread functions or related parameters.

Attributes Documentation

n_pix

The PSF’s effective number of pixels for the worse case where the PSF is centred on the corner of a pixel.

The effective number of pixels is for signal to noise calculations for PSF fitting photometry. The signal to noise for PSF fitting photometry is the same as if the signal were evenly distributed over this many pixels.

Returns:
n_pix : astropy.units.Quantity

Effective number of pixels

peak

The maximum fraction of the total signal that can fall in a single pixel.

This is simply the central pixel value of the PSF when it is perfectly centred on a pixel centre. This is useful for saturation limit calculations.

Returns:
peak : astropy.units.Quantity

Maximum fraction of the total signal that can fall in a single pixel, in 1/pixel units.

pixel_scale

Pixel scale used when calculating pixellated point spread functions or related parameters.

Returns:
pixel_scale : astropy.units.Quantity

Pixel scale in angle on the sky per pixel units.