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RealGalaxy Data
The galsim.RealGalaxy class in GalSim uses images of galaxies from real astrophysical data (e.g. the Hubble Space Telescope), along with a PSF model of the optical properties of the telescope that took the
images, to simulate new galaxy images with a different (must be larger) telescope PSF.
This modelling requires external data for the galaxy images and PSF models, which is read into a galsim.RealGalaxyCatalog object from FITS files. An example catalog of 100 real galaxies is in the repository itself. To get catalogs with large number of objects, the catalog to use depends on your GalSim version.
- For GalSim version 0.5 and earlier, a set of ∼26 000 real galaxy images (for galaxies with I<22.5), with original PSFs, can be downloaded from the following Public Dropbox folder:
Once you are at the Dropbox folder, download (1) the catalog file, (2) the 27 real_galaxy_images files, and (3) the 27 real_galaxy_PSF_images files. All files in the dropbox can be downloaded at once by clicking the Download box at the top right corner. (Clicking on individual files will not download the correct file.)
- For GalSim version 0.5.1 and later, a set of ~28 000 real galaxy images (a subset of galaxies for I<23.5), with original PSFs, can be downloaded from the GREAT3 server:
near the bottom, under "Other Data Files". The tarball is roughly 2 GB and contains catalogs and images with a README. Note that the file format differs somewhat based on GalSim updates.