JWST Cycle 4:

Changes to Proposals & Implications for Future Cycles

EURECA 9/20/24

Jackie Champagne, Lily Whitler & Jake Helton

JWST Cycle 3 - Total Proposals

Records were broken in Cycles 2 and 3 with 1,601 and 1,931 proposals respectively

38% went to Very Small/Small proposals; 38% to Medium; �25% to Large

​

​

JWST Cycle 3 - Science Category Breakdown

JWST Cycle 3 - Size Breakdown

Overburdening of panels and executive committees have led to significant revamping of Cycle 4 Proposals.

Quick info for JWST Cycle 4

• Deadline for all proposals: October 16, 2024 at 5pm Pacific
• Available joint proposals: ALMA, Chandra, HST, NASA, Keck, NOIRLab, NRAO, and/or XMM-Newton (double jeopardy)
• Expected allocations: ~1950 hours for Very Small, ~2900 for Small, ~2250 for Medium and ~1400 for Large/Treasury Programs (8500 total, 1.5x increase from Cycle 3 b/c of fewer observations from earlier cycles)
• Still dual-anonymous, careful not to reproduce too much text from previous accepted proposals as this technically violates DA
• No changes to 12-month exclusive access period, though this is under discussion

https://jwst-docs.stsci.edu/jwst-opportunities-and-policies/jwst-call-for-proposals-for-cycle-4/jwst-new-and-important-features#gsc.tab=0

New Proposal Science Categories: “Galactic” and “Extragalactic”

• Solar System
• Exoplanet Atmospheres and Habitability
• Planetary System Formation & Dynamics
• Stars & Stellar Populations (Milky Way)
• Gas, Dust & The ISM (resolved studies)

—-

• Nearby Galaxies to Cosmic Noon (z<3)
• High-Redshift Galaxies & The Distant Universe (z>3)
• Supermassive Black Holes & Active Galaxies (all redshifts)

Changes to Proposal Size Delineations

Time Allocation Committee (TAC) Breakdown:

• Very Small & Archival are reviewed asynchronously by External Panelists (5)
• Small & Medium are reviewed by Discussion Panelists
• Large, Treasury & Archival Treasury are reviewed by the Executive Committee, which is now split into Galactic and Extragalactic committees
• Expert Reviewers are called in to review a subset of the above proposals

https://www.stsci.edu/contents/newsletters/2024-volume-41-issue-02/a-high-level-guide-to-changes-in-the-jwst-cycle-4-call-for-proposals

Changes to Proposal Format

• Proposal page limits are basically cut in half. Science Justification, Technical Justification, and all figures must be contained in 4-6 pages (small→large)
• with +1 page for Special Requirements, Justify Coordinated Parallels, Justify Duplications and Justify Coordinated Observations with Other Facilities
• All must be in 12pt font within the TeX template, references do not count towards pgs
• These apply to all future DDT proposals as well

https://jwst-docs.stsci.edu/jwst-opportunities-and-policies/jwst-call-for-proposals-for-cycle-4/jwst-guidelines-and-checklist-for-proposal-preparation#JWSTGuidelinesandChecklistforProposalPreparation-pagelimits&gsc.tab=0

Major Updates to the APT

• IMPORTANT: Observing Description is no longer visible to TAC, only STScI, so you can’t cheat and put extra text that didn’t fit in Technical Justification in there
• New scientific categories and program size categories, multi-observatory flag
• NIRCam Grism Time Series Template available for SW and LW channels
• NIRCam Target Acquisitions updated for dithering and new hot pixels
• Optional target acquisition for MIRI slitless LRS
• Test scheduling now goes out to 5 years for multi-cycle proposals
• Reference star background observations are no longer proprietary
• Improvements to ICRS Coordinates and Fixed Target Resolver
• Proper motion must now be specified or listed as negligible for targets that need very accurate coordinates

https://stsci.service-now.com/jwst?id=kb_article&sysparm_article=KB0011960

Major Updates to the ETC

• Specifying single-group ramps is now a valid option for all non-target acquisition NIRCam, NIRISS, and NIRSpec modes.
• Thermal background model was updated (primarily affects MIRI observations, but also has small effects on longer-wavelength near-infrared observations)
• Entire PSF library was regenerated with distortion and other detector effects included
• MIRI: throughputs were updated to account for the count rate loss issue. SLITLESSPRISM subarray was added to MIRI imaging to support LRS Slitless verification imaging.
• NIRCam: Throughputs were updated based on on-sky observations. Short Wavelength (SW) Grism Time Series mode is now available in the ETC. LW Grism Time Series mode was updated to include options that are available when paired with the new SW mode
• NIRISS: saturation limits were updated for the AMI, Imaging, and WFSS modes
• NIRSpec: On-Target N-Point Nod strategy was added for NIRSpec IFU mode. Non-uniform wavelength sampling in the G395H dispersion file was corrected.
• Some other small improvements to usability… (e.g., aperture visualizations in images)

​

https://stsci.service-now.com/jwst?id=kb_article_view&sys_kb_id=7996fab593d746d0619dfe4c5cba10e9

More Information

Call for Proposals

High-Level Guide to Cycle 4 Changes

Release Notes for the ETC & APT

Example workbooks

Previously accepted proposal abstracts

Install APT & Download Tex Template

Cycle 3 TAC Report

Discussion

• Will the changes to the proposal format influence (decrease) the total number of submissions, since old proposals cannot simply be resubmitted?
• Will the new science categories (esp. extragalactic changes) change the allocation percentages to nearby vs. distant proposals?
• Will the executive committee split between galactic/extragalactic improve the quality/content of proposal reviews?
• Will the updated capabilities of e.g., NIRSpec IFU and declining use of MIRI influence the content of proposals or allocations towards specific science goals?

A Brief Runthrough of the Cycle 4 APT:�MIRI/LRS and NIRSpec/MSA

MIRI/LRS

https://jwst-docs.stsci.edu/jwst-mid-infrared-instrument/miri-apt-templates/miri-lrs-apt-template

MIRI/LRS

https://jwst-docs.stsci.edu/jwst-mid-infrared-instrument/miri-instrumentation/miri-optics-and-focal-plane

MIRI/LRS

https://jwst-docs.stsci.edu/jwst-mid-infrared-instrument/miri-observing-modes/miri-low-resolution-spectroscopy

MIRI/LRS

https://jwst-docs.stsci.edu/jwst-mid-infrared-instrument/miri-observing-modes/miri-low-resolution-spectroscopy

MIRI/LRS

https://jwst-docs.stsci.edu/jwst-mid-infrared-instrument/miri-operations/miri-target-acquisition/miri-lrs-slit-target-acquisition

MIRI/LRS

Zavala et al. (2024; arXiv:2403.10491)

MIRI/LRS

Zavala et al. (2024; arXiv:2403.10491)

MIRI/LRS MIRI/MRS

Hsiao et al. (2024; arXiv:2404.16200)

MIRI/LRS MIRI/MRS

Hsiao et al. (2024; arXiv:2404.16200)

NIRSpec/MSA – the source catalog

At minimum, the source catalog must include RA and Dec. Everything else (ID, magnitude, stellarity, etc.) is helpful but not required. The MPT will prioritize objects in the order they appear in the catalog.

​

Weights are helpful if you really want some particular object(s) on the MSA, but note that weighting your must-have objects as 10 will not guarantee a shutter gets opened on them so be excessive. The maximum recommended weight is 10⁹, so really, I promise. Be excessive.

​

Targets > Import MSA Source Catalog (make sure you’re in the Form Editor)

​

Or if you’re on the Targets page, the New button in the upper left corner also works

NIRSpec/MSA – the source catalog

If your catalog has a commented header, the APT will try to match your column names

to the names it recognizes. If it doesn’t, fill in the column names with the drop down menu.

If you “Ignore” a column, it won’t even be loaded into the APT.

NIRSpec/MSA – the source catalog

New Candidate Set lets you filter your

parent catalog (helpful for testing different configurations, defining primary and filler

target lists, etc.)

​

Astrometric Accuracy and

Pre-Image Availability are required

NIRSpec/MSA – the MPT

The MSA Planning Tool (MPT; navigate to it in the top toolbar) is both your best friend and your worst enemy

​

Primary Candidate List = drives the pointings

​

Filler Candidate List = the MPT will check if any shutters can be opened on these targets after the pointings are set by the Primary Candidate List but these are just bonus objects and don’t set the pointings

​

Aperture PA = a large reason of why the MPT is your worst enemy. You cannot search for solutions over multiple PAs. Which is great when your program is actually being observed and a PA has been assigned, less great when you’re trying to figure out what you can do for a proposal.

NIRSpec/MSA – the JWST GTVT

The APT won’t even let you try a PA that’s genuinely impossible, but the JWST General Target Visibility Tool may be helpful if you don’t want to have to guess what is possible: https://github.com/spacetelescope/jwst_gtvt

​

jwst_gtvt --ra=03:32:36.89 --dec=-27:46:49.33 --instrument nirspec

NIRSpec/MSA – back to the MPT

3 Shutter Slitlet is pretty standard and you probably want to nod in the slitlet

​

Choose your disperser and filter combination https://jwst-docs.stsci.edu/jwst-near-infrared-spectrograph/nirspec-instrumentation/nirspec-dispersers-and-filters#gsc.tab=0

​

You can apply various masks if you want to make sure the entire spectrum ends up on the detector (n.b. higher resolution = more pixels, prism and medium resolution grating spectra can fit all on one detector in a limited number of shutters, high resolution cannot and the detector gap is unavoidable)

​

This restricts the available shutters and the APT gives you an MSA Target Info file with information about where a spectrum has been cut off, so perhaps better to check wavelength coverage manually for the sources you care the most about.

NIRSpec/MSA – the MPT

Set your parameters for how you want the MPT to search. It’s

parallelized but huge numbers of pointings will still take forever to check.

NIRSpec/MSA – the MPT

There is a separate tab for plans that the MPT has found. Once you have one

you’re satisfied with, you can “Create Observation” and choose your readout pattern, etc.

NIRSpec/MSA – creating the observation

NRSIRS2 is the readout pattern I most commonly see used and the IRS² readouts (NRSIRS2 or NRSIRS2RAPID) are recommended in general. NRSIRS2 reads out four frames per group, RAPID reads out one frame per group and is a much higher data volume. You choose the number of groups per integration and the total number of integrations.

Coordinated parallels possible with NIRSpec MOS prime and NIRCam or MIRI imaging parallel. NIRSpec MOS cannot be the parallel observing mode (either coordinated or pure parallel).