Galex Release EMphot 3

The Galex Release EMphot 3 (GREM3) gives access to the GALEX GR6 data from the Deep Imaging Survey (Texp > 30ksec /field) reprocessed with the EMphot photometry software. The EMphot algorithm use optical priors with UAB < 25~26 based on the T0007 release of the CFHTLS.

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Photometry of astrophysical sources in crowded field images

EMphot (formerly PPrior) is a software for the photometry of astrophysical sources, galaxies and stars, in crowded field images. Its goal is to estimate the flux in a low resolution band using prior information (position and shape) from a better resolved band, in a Bayesian approach under the Poisson noise assumption. The solution is reached with an Expectation-Maximization (EM) algorithm for solving the photometry and includes several steps: prior shapes deblending in high resolution images, astrometry correction, PSF optimization, background correction from the residual.

More details

Main changes since version 2.0

  • Update input data to GALEX GR6 and CFHTLS T0007.
  • Combine multiple prior catalogs for one GALEX field (useful for CFHTLS W1).
  • Improve simulations : stamps, follow the density of the field, add sources in the processed area.
  • Improve comparison plots.
  • Change the psf.
  • Recentering done with likelihood minimization.
  • Lot of bugfixes and code improvements.