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This page archives Slack comments from the splinter session on spectral extraction of the Improving JWST Data Products Workshop (IJDPW).
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Jeff Valenti
Thu and Fri of the workshop this week will be a hands-on exercise comparing data products generated by the community and the STScI pipeline. The organizing committee has suggested that we meet (virtually) on Thursday (1:30-4:30 EST) to discuss spectral extraction. We can work asynchronously before and after that.Some questions we may want to address:
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some tweaks for the extraction of MSA spectra that I think would be great to have:
1) as discussed in another channel, a wavelength correction for the fact that sources almost never fall in the centre of the shutter can really help with the extraction of faint emission lines of compact sources. This wavecorr is currently already computed to perform the flat fielding, but then not propagated further in the pipeline.
2) the "bounding box" used for the extraction is very tight, e.g. when opening 3 shutters the extraction box is only 15 pixels, meaning that at long wavelengths some flux is missing. As a user it would be nice to have a free parameter that you can set to extract a slightly larger aperture in the cross-dispersion direction, rather than having to hack the *msa.fits file to add fake shutters in order to trick the pipeline. Looking at the source code, I think this should be possible, I just don't know how I would do it as a high-level user. Same goes for the dispersion direction - occasionally we see lines at 5.3-5.4 micron in NIRSpec, but the pipeline can't extract it (I know this will be harder to implement than the spatial direction).
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Jean-Baptiste Ruffio
FYI: Continuum normalized spectrum extraction we use to very accurately identify bad pixels
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