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Issue with NIRSpec barshadow correction in MOS long slit data #8942

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stscijgbot-jp opened this issue Nov 4, 2024 · 2 comments
Open

Issue with NIRSpec barshadow correction in MOS long slit data #8942

stscijgbot-jp opened this issue Nov 4, 2024 · 2 comments

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@stscijgbot-jp
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Issue JP-3796 was created on JIRA by Christian Hayes:

As a result of looking into helpdesk ticket INC0205578 (PID 5064 obs 1) we noticed that there is striping in calibrated MOS long slit data, which appears to be an aliasing effect of a mis-aligned bar shadow correction.

I've attached an example here (jw01444003001_04102_00001_nrs1_cal, reduced with jwst 1.16.0, jwst_1298.pmap) showing cal spectra with barshadow correction on on the left and no barshadow correction on the right (where the barshadow can be seen as the periodic dip in light in between shutters).  It appears that the mis-alignment is less severe along some parts of the longslit.  The spectra in the barshadowed region between shutters looks smoother near the top of the screen shot - though there may still be some residual barshadow correction that isn't quite right.  Towards the bottom of the screen shot, the barshadow appears to be misaligned with the shutters, amplifying the barshadow effect.

@stscijgbot-jp
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Comment by David Law on JIRA:

Christian Hayes Is this something that just requires a reference file update, or is there something about the code that also needs to change?

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stscijgbot-jp commented Nov 4, 2024

Comment by Christian Hayes on JIRA:

I believe this is a code related issue, because the barshadow reference files are for a single shutter or a 3-shutter slitlet and the code will use these to stitch together the appropriate number of shutters to make slitlets of variable length (so it looks like the stitching isn't scaling up correctly).

 

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