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0 What we expect from perfect alignmentfocus

I generate the psf stars from Steve's raytracing model by assuming perfect alignment and perfect focus. For each CCD, I place 5 stars at random position. For the focal plane, there are altogether 62 x 5 = 310 psf stars in the analysis. In addition to the optics PSF, I assign each star a circular Gaussian seeing with fwhm = 0.7 arcsec. I did this for g, r, i, z band and at zenith angle 0, 20, 40 and 60 degree. In the measurement, I use the weighted moments with a kernel size of 2 pix. Then, the weight contribution is subtracted from the moments. The R50 is defined as 1/2 of the fwhm. Whisker is defined as [(Ixx - Iyy)^2 + (2*Ixy)^2]^{1/4}

  • zenith angle = 0 degree
    • g band
    • r band
    • i band
    • z band
  • zenith angle = 20 degree
    • g band
    • r band
    • i band
    • z band
  • zenith angle = 40 degree
    • g band
    • r band
    • i band
    • z band
  • zenith angle = 60 degree
    • g band
    • r band
    • i band
    • z band