## PZ-G2 » History » Version 2

Huan Lin, 10/14/2012 07:53 PM

 1 2 3 1 Huan Lin `h1. PZ-G2, PZ-G3, PZ-G4` 1 Huan Lin 1 Huan Lin `* PZ-G2: (Photo-z – spec-z) bias has been plotted against photo-z in bins of width dz=0.1.` 1 Huan Lin `* PZ-G3: Photo-z sigma and sigma68 vs photo-z has been compared against R-8.` 1 Huan Lin `* PZ-G4: Outlier fractions vs photo-z have been compared against R-23.` 1 Huan Lin 1 Huan Lin `h2. Prerequisites` 1 Huan Lin 1 Huan Lin `DESDM photo-z module neural network photo-z outputs for VVDS-Deep data obtained under goal [[PZ-G1]]` 1 Huan Lin 1 Huan Lin `h2. Procedure` 1 Huan Lin 1 Huan Lin `Use existing IDL code from [[des-photoz:DC6_Photo-z_Challenge|DC6 Photo-z Challenge]], which will:` 1 Huan Lin `# Divide sample into photo-z bins of width dz = 0.1` 2 Huan Lin `# Calculate and plot mean of (photo-z - spec-z) vs. photo-z [[example plot|attachment:sv_test_comp_bias.ps]]` 2 Huan Lin `# Calculate and plot sigma = standard deviation of (photo-z - spec-z) vs. photo-z ` 1 Huan Lin `# Calculate and plot sigma68 = 68-percentile (photo-z -spec-z) vs. photo-z` 1 Huan Lin `# Calculate and plot 2-sigma and 3-sigma outlier fractions, defined relative to sigma, vs. photo-z` 1 Huan Lin 1 Huan Lin `h2. Verdict` 1 Huan Lin 1 Huan Lin `# Check against DES science requirement R-8 that sigma68 < 0.12` 1 Huan Lin `# Check against DES science requirements R-23 that 2-sigma fraction < 0.1 and 3-sigma fraction < 0.015` 1 Huan Lin 1 Huan Lin 1 Huan Lin `h2. Consequences` 1 Huan Lin 1 Huan Lin `Results from [[des-photoz:DC6_Photo-z_Challenge|DC6 Photo-z Challenge]] indicate that the above requirements should be met or close to being met. If we see significant differences for the real VVDS-Deep data, we will investigate potential causes, starting with:` 1 Huan Lin 1 Huan Lin `# Potential systematic trends in DES colors/magnitudes vs. RA,Dec, checked by plotting DES photometry vs. existing VVDS or CFHTLS (truth-table) photometry of the VVDS-Deep field` 1 Huan Lin `# Potential lack of depth in the DES coadd data for the VVDS-Deep field, checked by comparing the sky background noise, seeing FWHM, and photometric zeropoint in the DES coadd images vs. the respective nominal DES main survey full-depth values`