Meeting agenda:

  1. News & Announcements (all)
  2. Roundtable Cycle 2 calibration plan updates (all)
  3. Handling LRS SLITLESSPRISM 390 Hz noise (Regan)
  4. TSO WG work (TSO monitors, non-linearity, 1/f, etc.; all)
  5. Roundtable check-in

Discussion items

5 mins

1. News & announcements


Nestor Espinoza : some cycle 2 stats. huge increase in exoplanet proposals compared to cycle 1 (not all TSOs)

the TSO modes are heavily requested as well: esp NIRSpec BOTS

TSOs are ~20-30% of JWST usage for cycle 2 proposals (yay and yikes)

2. Cycle 2 calibration plan check-in

Cycle 2 calibration plan is not yet fixed - mission office will review the programs before assigning PIDs. 



  • Program on grism backgrounds
  • Mario will try to add a program similar for NIRISS and to Grism backgrounds for the DHS mode.


  • not a dedicated program but we have requested dedicated backgrounds for all LRS slitless cal observations
  • some detector calibration activities will also feed into our TSO performance. 


3. 390 Hz noise for MIRI

Slides from Eddie & Mike. 

Noise is actually present in all array configurations, but in most array configs the noise is in phase (which occurs when npixels in subarray is a multiple of 256) . Very visible in SLITLESSPRISM. 

Initial fix from Ressler is to move the subarray, increasing frame read time by 8%

Eddie created a library of solutions with various compromises. Some even shorten the frame time. 

Quite an impactful change, need to start the transition asap - we need consensus and buy in from stakeholders asap. We should not accept having this additional noise in the data for the lifetime of the mission - we would not have picked this for flight had we known about it. 

SK: like the smallest size where we gain 6.6% read time

NE: what is the cost?

  • anything that has a time calculation will need updating so it's quite impactful

NE: how well can we correct it in data?

  • you have to solve for phase, it can be done but it's not easy. definitely hard to implement in the pipeline
  • several community members have reported back that there is some residual noise.

We need to quantify with some numbers for the trade-off for this work to assess whether it's worthwhile doing. 

LA: should we optimize the subarray size to maximize the background coverage if that is proving problematic?

  • yes the LRS group will have to look into the optimal size - comparing the background coverage against the wavelength range. 

ES: can we make a new subarray to avoid the shadowed region?

  • yes that can be part of the equation. we can move the subarray up & down with no additional impact, moving horizontally has more of a frame time cost. 
  • MR: also looking into the initial conditions for the observations, eg the shadowed region

4. TSO Work Nestor Espinoza 

TSO monitor Nikolay Nikolov :

  • no major updates; code running every 12 hrs (4 hrs was a bit too much)
  • difficulty getting responses from ITSD for this to become hosted on the webpage (requiring SSO login; not public)
  • workaround: emailing it round.
  • some issues with the visit status reports, esp if there was a failure of some kind. sometimes when replacement obs is generated it can take a long time for the visit status to be updated online.

Bad pixels/NaNa Nestor Espinoza :

with newest version of the pipeline bad pixels are converted to NaNs. newest processed data shows a LOT of NaNs, more than expected. Probably related to new bad pixel map. 

5. Roundtable check-in




2 mins4. Closing Remarks