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Astrometry » History » Version 6

Robert Armstrong, 12/22/2012 06:38 AM

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h1. Astrometry
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h2. Clipped Objects
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I have looked at the objects that were clipped from the starflat3 fit as a function of various quantities.  
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!{width:400px}clip_xy.png! !{width:400px}clip_focal.png!
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!{width:400px}clip_err.png! !{width:400px}clip_band.png!
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Some observations:
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# Many of the clipped objects lie at the y edges of the chip
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# More objects are clipped from the right side of the focal plane.  CCD 7 has the most clipped objects.
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# Most of clipped objects have the minimum pixel uncertainty of 0.01 from the fit.
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# It doesn't vary too much from band to band.
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Here is the number of clipped objects as a function of exposure.  There seems to be a common pattern probably determined by the dither pattern in the different bands.
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!{width:900px}clip_exposure.png!
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There is one exposure that has more objects clipped than any of the others, this is DECam_00153751.  Here are the clipped objects as a function of the focal plane.
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!{width:400px}DECam_0153751_focal.png!
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It looks like a poor fit over the exposure.