8.5 Target-Specific Problems
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Fig. 8.7 Surface plot of a bright star within Fig. 8.6 using SalsaJ. The dome-like structure of the
plot suggests that the star lies within the nonlinear region of the CCD. A flat top, as opposed to a
dome, would indicate saturation. Note the smaller peak, which is much more Gaussian-like than
the larger peak. This is a dimmer star within the region of the plot, and its Gaussian nature indicates
that its pixel values lie completely within the linear region of the CCD
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Fig. 8.8 A slice though a bright star within Fig. 8.6 using SalsaJ. The large peak is clearly nonGaussian, indicating that it lies within the nonlinear region of the CCD (a flattened peak would
also indicate saturation). The small peak is from another star also in the slice. This appears broadly
Gaussian in nature as we would expect and hence lies in the linear range of the CCD