Astronomical image analysis often requires knowledge of the point spread function (PSF), or response of an imaging system to a point source, in order to understand the shape of emitted sources. The PSF can be measured using images of unresolved sources, but can be heavily affected by sampling effects for large detector pixels. For cases where the PSF is largely concentrated into a single pixel, this undersampling poses a challenge. However, as in a typical astronomical image many realizations of images of unresolved sources are placed randomly on the detector's pixel grid, these images can be combined to reconstruct the sub-pixel PSF via a method commonly referred to as "stacking." We have developed a new method to reconstruct undersampled PSFs using a stacking technique, and tested it using both the ideal case of noiseless Gaussian point sources, as well as simulated data with complex PSFs for the upcoming SPHEREx mission. We discuss methods to mitigate the effects of noise and detector pixelization on the reconstructed PSF, and demonstrate this method's usefulness in obtaining photometry of unresolved sources.
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020