I finally got some JWST NIRSpec data for a project, and I'm trying to work through the official JWST data reduction pipeline. I've followed the documentation, but my final spectra look... off, especially around some of the artifact corrections. I'm not sure if I'm misunderstanding a step or if there's a known quirk with the pipeline version I'm using. Has anyone else hit a wall like this and found a good way to sanity-check their results?
I've wrestled with JWST NIRSpec spectra that looked off after artifact corrections too. A solid move is to sanity-check by stepping through intermediate products: compare 2D calibrated data with the raw, overlay the wavelength solution, and run a small subset through a known-good reference file. Also check if your pipeline version has any known quirks; sometimes a dash of cross-validation with a standard star or simulated spectrum helps reveal where things drift.
Feels like a moving target to me; maybe the problem isn’t the steps but matching them to your data. The artifact corrections can look wrong if the context is off. Try a minimal run with minimal reference files and see if the spectrum improves; if not, it might be something odd in the data.
One concrete sanity check is to re-run a tiny chunk of data with a different calibration file and compare outputs. If the shapes disagree, that flags a calibration or header issue rather than data physics. Also plot the residuals around the suspected artifacts and quantify any offsets.
Have you tried cross-checking with a synthetic spectrum pushed through the same reduction steps? It can reveal if the quirks are in the pipeline vs in the data; or you can run a side-by-side of two reductions from different pipeline versions.
I know the feeling; sometimes the workflow itself introduces artifacts more than the instrument does. It helps to document one figure of merit you care about and see how much each stage changes it; if artifact-correction steps barely affect that merit, you might be chasing noise.
If you want, paste a short snippet of the log or describe which artifact correction behaved oddly and which version you’re using. We can brainstorm a few targeted checks and maybe flag a likely culprit without guessing too much.