Introduction to Image Reduction
Introduction to Image Reduction
Introduction to Image Reduction
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Motivation & background Instrumental Signature Removal Combining multiple images Pho<strong>to</strong>metric calibration<br />
Caution for wide-field cameras<br />
The pixel size (as projected on the sky) changes from center <strong>to</strong><br />
edge in wide-field cameras, due <strong>to</strong> optical dis<strong>to</strong>rtion.<br />
Pixels at corners subtend less sky and appear fainter on sky flats,<br />
but do not collect fewer pho<strong>to</strong>ns from stars and galaxies!<br />
Model the optical dis<strong>to</strong>rtion <strong>to</strong> remove this effect.<br />
Also account for this effect when repixelizing on<strong>to</strong> a uniform grid!<br />
(See, eg, Mosaic data reduction manual for a more detailed<br />
explanation.)
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