def FWHMgeom2FWHMeff(FWHMgeom):
    """
    Convert FWHMgeom to FWHMeff.
    This conversion was calculated by Bo Xin and Zeljko Ivezic (and will be in an update on the LSE-40 and overview papers).
    @param [in] FWHMgeom (the geometric FWHM value, as measured from a typical PSF profile) in arcseconds
    @param [out] FWHMeff (the single-gaussian equivalent FWHM value, appropriate for calcNeff) in arcseconds
    """
    FWHMeff = (FWHMgeom - 0.052) / 0.822
    return FWHMeff
