Webb Office Hours Session 38: September 25, 2025
Q&A's:
Q1: Where are the Webb Office Hours procedures and guidelines?
A1: Webb Office Hours. Type your question into the WebEx chat. We will asynchronously copy questions from the chat to this main page and work through them as a group. If you have images to share please give WebEx permission to share your screen (you may need to log out and log back in again to enable this feature.)
Q2: Related to open help desk ticket. Attempting to reproduce data reduction for a target from PID 2926 but cannot find the Halpha line. These data were previously published but they use a different extraction technique where a constant aperture size is used (compared to the pipeline, which uses a wavelength-dependent aperture radius) and use 20 apertures within the field to perform background subtraction. Even following the same procedure, the published results cannot be replicated. Halpha should be at ~7.6 micron for this target.
A2: Ticket was recently reassigned, may see movement soon. Might help to use a custom bad-pixel mask and Spec2 straylight clean shower correction (latter already being done), since the target is at a high redshift (z~11) and is really faint. Sounds like many other steps have already been taken, so increasing the SNR will come down to small tweaks and optimizations. Shrinking the aperture could help, as it reduces the noise. => But already using the aperture size given in the paper. User will talk offline with David Law.
Q3: NIRSpec data for very extended faint emission but cannot see it with the current pipeline calibration. How can we improve the SNR in these regions? Removing 1/f noise didn't seem to help, tried using both clean_flicker_noise and NSClean. Also, the flux seems to drop-off unexpectedly longwards of the detector gap.
A3: The drop-off could be due to the background subtraction, but it is strange that the NRS1 and NRS2 detectors are being handled differently. Should also choose to use either, but not both, of clean_flicker_noice or NSClean. Based on lines detected with MIRI, features should be seen with NIRSpec. Not much is showing up in the _rate files, which means nothing will show up in the _s3d files. Should check the pointing and orientation of the NIRSpec data, then look at the MIRI data to determine the brightness there. Appears to be a "picture frame effect" with the NRS2 data, which could be causing issues. Suggest using the stage 1 1/f correction (clean_flicker_noise).
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