Webb Office Hours Session 10: June 27, 2024
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: I have MIRI data and had previously been using jwst_1235.pmap reference files. I just updated to using jwst_1238.pmap, however, now I have lots of NAN pixels. Could this be due to the new reference files?
A2: The 1238 delivery updates MIRI MRS flatfield and photometric calibration reference files, but not aware of any new masking (see https://jwst-crds.stsci.edu/). The NAN pixels appear to be perfectly aligned with your targets, so we think something else might be going on. Please send us a Help Desk ticket with your Program ID number and appropriate screens shots so we can investigate further.
DRL update: On digging into this I think the issue is with calwebb_detector1. The relevant line is ultra-bright, and it looks like the CR shower algorithm is mistaking it for the core of a cosmic ray shower and flagging sections of the source around it. This would only affect offline reprocessing since the showers code is OFF by default for MRS. This would be unaffected by reference file updates though, so unclear why the pmaps above made a difference.
Q3: In my MIRI MRS data (of 3 galaxies) there is a noticeable absorption feature on the sides of the Ar II emission line at 7 microns. This feature is present in all of my data across the cubes, is this real or perhaps a detector artifact? The Ar II line is very bright, especially in channel 1, but not brighter than other emission lines in my data.
A3: How are you doing background subtraction? It could be that there is an emission feature that is making it into the master background and being subtracted off. This does not seem to be the case for you and it is strange that it is moving around. Please submit a Help Desk ticket to the MIRI team and we will look into it in more detail with you.
