Data Reduction Frequently Asked Questions

My spectrum of a bright source looks much noisier than I expected - why?


Bright spectra observed in very good seeing have very steep slopes and may be flagged as cosmic ray hits. During the extraction the pipeline then creates a large number of spikes in the regions flagged as cosmic ray hits. This problem can be solved by switching off the cosmic ray detection, i.e. setting removecrhsingle-niter to 0.
The figure shows an example of this effect and its correction. Due to the better seeing at longer wavelengths the effect is mostly found for NIR data.