Webb Office Hours Session 26: March 27, 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: Looking at the flicker noise step of the pipeline for NIRCam data; Narrow band structure goes away, but there are still some softer noise around the edges on a crowded star field. Asking if there is any additional improvement that can be done. The parameters being used are: fit method = median and background method = model; fit by channel might have made incremental change; big blocks of the image that are different background levels.
Is there a scale size parameter option?
A2: There's a current known issue where clean_flicker can make skymatch worse sometimes (https://jwst-docs.stsci.edu/known-issues-with-jwst-data/nircam-known-issues/nircam-1-f-noise-removal-methods#gsc.tab=0 & "Program 1783 - Check skymatch results"). It might be worth trying to use median background (for the bottom right panel especially). For best results, might have to try working with different parameters for different regions.
There is a scale size parameter option: --background_box_size (list of int, default=(32,32)); All arguments are at: https://jwst-pipeline.readthedocs.io/en/stable/jwst/clean_flicker_noise/arguments.html
Tips & tricks for image aligning: https://jwst-docs.stsci.edu/known-issues-with-jwst-data/nircam-known-issues/nircam-imaging-known-issues#gsc.tab=0
Q3: Are there parameters in the jump detection to remove remaining cosmic rays in images?
A3: The jump detection parameters can be changed: https://jwst-pipeline.readthedocs.io/en/stable/jwst/jump/arguments.html ; or you can change parameters snr threshold in the outlier detection https://jwst-pipeline.readthedocs.io/en/stable/jwst/outlier_detection/arguments.html as well
Q4: Jupyter notebook screen goes blank after a while
A4: Our best guess is this is due to the log being too long. Should be able to port the output to a log file (https://jwst-pipeline.readthedocs.io/en/stable/jwst/user_documentation/logging_configuration.html). Could also try:
If you add lines like this to the top of your jupyter notebook it should turn off some of the logging in the notebook which may keep it from going to a white screen:
import logging
logger = logging.getLogger()
logger.setLevel(logging.CRITICAL)
Q5:
A5:
Q6:
A6:
Q7:
A7:
