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15 Uncertainty on moments measurements

I did some simulation to test the uncertainties on the moments measurement using different methods, weighted or non-weighted. The simulation is generated as following:

  • I choose both symmetric Gaussian and Moffat profile, with fwhm = 0.7 arcsec (and beta = 3.5 for the Moffat profile).
  • assume gain = 0.21 adu/electron, pixel scale = 0.27
  • assume r band sky level, 8.460140*exptime [photons]
  • assume r band star photons: exptime*10**(0.4*(26.794176 - mag))
  • Possion noise are added

Then, I run both weighted (2 pix weight kernel) and non-weighted moments for 1000 realizations under different star magnitude and exptime, the results are as following (the unit is pix^2 on the plot, Mcc is the moment along the column direction, Mrr is the moment along the row direction):

  • Gaussian PSF
  • Moffat PSF