sfarrens
commented
3 years ago @sfarrens notes:
- PSFEx (for HSC)
- pixel-based PSF from single expsoures
- Co-add PSFs
- Pixels of postage stamp used as a PSF model
- What are basis vectors for pixel-based PSF?
- Features of the PSF that you learn
- LensFIT
- PSFEx only works on independent images (or CCDs)
- LensFITS can handle the full field of view
- Similar basis to PSFEx
- Weighting of stars
- Intra-pixel shift
- PIFF (for DES)
- Similar to PSFEx
- Modelling in sky coordinates instead of pixel coordinates
- because of astrometric distortions
- smoother variations in sky coordinates?
- Basis-function polynomial for interpolation of PSF model
- Delayed solution
- don't need to solve for the PSF at the position of each star
- use common information for all single exposures to improve model
- Tree ring pattern
- strong for some CCDs, but not for others
- Gaussian processes not implemented for Y3
- potential best solution for atmospheric distortion
- PIFF has a modular implementation
- MCCD
- Aim to capture global and local features
- Denoising terms
- Radial Basis Function (RBF) interpolation of weights to galaxy positions
- Discussion
- Hard to make pixel grid that makes sense for entire focal plane
- sky coordinate grid potentially a better solution, but this is on a sphere
- CCD-specific models important for discontinuities
The objective of this issue is to gather notes on the various methods for modelling a PSF discussed during the reading group.