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Agenda

  • News & announcements  
  • Previous & upcoming TSO observations 
  • Rundown of Cycle 4 programs 
  • TSO sprint updates 
  • DHS pipeline recommendations
  • MIRI subarray discussion  
  • Closing remarks

Discussion items

TimeItemWhoNotes

2 min

News & AnnouncementsAll
 
  •  some DHS programs in Cycle 4, including for a super-Earth!
  • the MULTISTRIPE code has been uploaded
5 minPrevious & upcoming TSO observationsCarter
 
  • executed: MIRI/LRS observations of a BD and NIRSpec BOTS observations from a GTO program
  • upcoming: BOTS observations
  • no TTRB highlights!
10 minRundown of Cycle 4 programs Carter
  • breakdown of Cycle 4 results by mode/instrument 
  • some highlights: NIRSpec BOTS accounts for ~43% of the C4 observations, DHS takes up ~5%
  • ~800 hours for giant planets, 530 for terrestrials, 260 for sub-Neptunes, ~50 hours for host star characterization
  • both exoplanet categories still comprise ~30% of JWST time 
5 minTSO sprint updatesCarter
  • goal is to have a target that is representative of a "typical" observation and analysis
  • cross-mode target would be useful for comparison - W39b and W107b are currently the best targets
    • but W39 PRISM data are saturated
    • better behaved PRISM target - Kepler-51b? (but short post-transit baseline, so not a typical target) 
    • MIRI photometry target - TRAPPIST-1b if we select the deep eclipse? (can see the eclipse in a single visit, although known variability as well).
      • can also grab some segments from a portion of phase curve.
      • actually, let's do a MIRI photometry transit  of a TRAPPIST target (PID: 3077)
  • Kepler-12 has a well-behaved PRISM dataset, no stellar activity, some variability across the visits (PID: 3969)
  • so, for the sprint we are planning to use these datasets: Kepler-12b (PRISM), TRAPPIST-1 (MIRI photometry), WASP-39b (all other modes)
20 minDHS pipeline recommendations Stansberry
  • DMS has generated some DHS uncal products for pipeline developments, now we need to layout what steps we want them to carry out for NIRCam/DHS data 
    • need to think about some pipeline steps like the jump step that will flag neighboring pixels, and come up with workarounds
    • accidentally flagging a pixel from another spectrum as charge migration would have a minor effect 
  • we'd like the entirety of Stage 1 for DHS data analysis, implementing everything in the TSO column 
  • for Stage 2, we'd also want the entirety of stage 2 since the C4 DHS programs will likely want flux calibrated spectra  
    • stage 2 outputs should be n number of spectra 
    • SOSS is in the process of making separate files for individual spectra, so DHS folks should be looped in on tickets related to those x1d products 
  • Achrene: should the pipeline combine the spectra or should folks handle this themselves? perhaps this could be done in a way to the S2 cube build steps, which are used in other modes
    • the separate spectra would be useful for systematics investigations, since the wavelength/flux calibration and throughput is different for each spectrum 
  • need to set PI expectations appropriately for the C4 DHS programs, since they are shared risk 
  • (if there are FTEs to do Stage 3, then it can be supported (but it's not urgent/necessary at the moment)
  • recommendation to DMS resulting from this discussion: ask them to run all steps for Stages 1 & 2, don't worry about neighboring pixel effects 
  • the cross-dispersion footprint is different for each spectrum since they are on different rows on the detector (and thus see different regions of the sky) 
    • the spectra are on a small subarray, so how much of an effect on the background would +/-10 rows (40 pix = 1.2 arcsec) have since the backgrounds would each have a different structure?
    • this info would need to be captured in a cal file, but we can hold off on implementing this for C4 (and make sure that we communicate this to the PIs
  • the contamination might be an issue for DHS, would this be helpful for different stripes?  
    • there is a distortion map for SOSS, could something similar be implemented for DHS?
  • we can use an engineering imaging template for the backgrounds, or include a background spectrum in the wavelength & flux cal programs (as was done for SOSS and MIRI LRS)
10 minMIRI subarray discussion 
  • altering MIRI subarrays and effect on TSOs - but some considerations of a subarray change
    • subarray area has to be in multiples of 64
    • clocking and readout considerations (why we have EMI at 390 Hz in some subarrays)
    • what else the pixels are used for during other observations 
  • affected subarrays
    • LRS slitless, imaging SUB128 & SUB64
    • MASKLYOT, MASK1065, MASK1140, MASK1550 (coronograph) 
  • LRS slitless can be changed to avoid 390 HZ noise by either:
    • trimming pixels on the left edge (they aren't used for science, so we can eliminate or shift to the right) 
    • trimming pixels from the top (below ~4.5 microns, the wavelengths are all overlapping, so very low resolution - can gain frame time here)
    • trim pixels from the bottom with 2 options
      • ~10.5 microns cutoff that will include silicate feature
      • ~12.2 micron cutoff to include NH3 feature
      • can include both options to maximize science
  • trimming pixels generally increases frame time, great for bright targets!
  • moving LRS slitless - keeping it on the left will keep frame times low 
    • can move it up to completely cover the LYOT and can remove shadow region - but need to consider SUB128 and SUB64 effects
      • shadow region effect causes crazy ramps in the data 
      • there's also a glow stick effect for the LYOT as well
    • can move it down to 4QPM subarrays - but consider glow stick effects and small gaps between phase masks 
  • imaging subarrays 
    • trim 8 pixels on the left edge that are unused ref pixels and blank pixels - need to adjust the exact size of the subarray to avoid the 390 Hz noise 
    • center star on 64x64 subarray 
    • move the subarrays?
      • moving vertically doesn't change frame time 
  • next steps
    • Hannah & Taylor wil provide short and long wavelength LRS cutoffs 
    • Hannah will provide imaging wishlist for SUB64 and SUB128, which Mike will use to find possible subarray sizes and locations that avoid 390 Hz noise  
    • offer TSO CT a subarray menu of recommendations 
    • timeline: move quickly as possible, have the options available for Cycle 5 
5 minClosing remarks

Action items