calc_neff¶
- rubin_sim.phot_utils.calc_neff(fwhm_eff, platescale)¶
Calculate the effective number of pixels in a single gaussian PSF. This equation comes from LSE-40, equation 27. https://docushare.lsstcorp.org/docushare/dsweb/ImageStoreViewer/LSE-40
- Parameters:
- fwhm_eff: `float`
The width of a single-gaussian that produces correct Neff for typical PSF profile.
- platescale: `float`
The platescale in arcseconds per pixel (0.2 for LSST)
- Returns:
- nEff
float
The effective number of pixels contained in the PSF
- The fwhm_eff is a way to represent the equivalent seeing value, if the
- atmosphere could be simply represented as a single gaussian (instead of a more
- complicated von Karman profile for the atmosphere, convolved properly with the
- telescope hardware additional blurring of 0.4”).
- A translation from the geometric FWHM to the fwhm_eff is provided in fwhm_geom2_fwhm_eff.
- nEff