Debugging — Cosmic Cookery

Pychelle debugging

Sawtooth pattern

Sample extractions of spectra from HIRES. The different colors represent different widths of integration along the same order in four instances. If the width is too narrow, a sawtooth pattern emerges. Notice the blaze function has not been removed f… — Sample extractions of spectra from HIRES. The different colors represent different widths of integration along the same order in four instances. If the width is too narrow, a sawtooth pattern emerges. Notice the blaze function has not been removed from these samples.

This pattern emerges due to the discretized nature of the pixels on the detector. In addition to producing integer numbered counts, the physical, non-infinitesimal size of each pixel results in over-integration or under-integration of the counts as the sub-pixel precision trace function moves across the image. "Sub-pixel precision" meaning that the trace function can include decimal places while the pixels only report integer (X,Y) positions.

The sharpness of the sawtooth pattern seen across the detector may depend on how curved the trace function is. The pattern begins to disappear at sufficiently wide integration widths because the amount of light in the inter-order regions is reduced to the bias or detector noise level and is no longer correlated with the order or the trace function.