Tile dependence of PSF in the SN Field Coadds » History » Version 3

William Wester, 02/12/2014 04:44 PM

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h1. Tile dependence of PSF in the SN Field Coadds
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In addition to tile dependence of S/G separation in the SN Fields, there is evidence of tile dependence of the psf model in the SN Field Coadds as demonstrated by the
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following plot.
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In 100 x 100 bins in RA and dec, for each of the SN fields, plot the average in each of the bands for stars (CBDT algorithm of S/G challenge) with mag_psf < 22,  the following:
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δ mag = mag_psf – mag_auto
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where the quantities come from the SVA1_COADD_SNx database.    
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For brighter stars, you expect mag_psf and mag_auto to agree very well average near  δ mag = 0. Indeed, most of the area in the SN fields are green/white near 0. However,
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you see unusual regions that seem to match title boundaries. Although the region in g-band for the E field is particularly unusual. It's fairly important in that the mag_psf
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can be wrong by magnitudes exceeding the color scale of the plot (which is 0.2). In fact, in the upper right plot, mag_psf in the unusual region sometimes differs up to 
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1.5 or 2 magnitudes from mag_auto. I should point out that mag_auto appears to be consistent with the magnitudes obtained in the Single Epoch SVA1_FINALCUT catalog.
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!{width: 1000px}deltamag.png!