Major events or important changes in the JWST mission are posted in dated sections of this article.
For a list of new JDox articles and updates to existing articles, please go to JWST JDox Latest Updates.
On this page
22 August, 2024 update
Release of APT 2024.5.1
APT 2024.5.1 is now available for Cycle 4 proposal preparation. You can download it from the APT website. Release notes are available at the JWST Helpdesk website.
New NIRCam time-series capability now available
A new NIRCam capability that allows grism time-series observations in the short wavelength (SW) channel is available to the scientific community in Cycle 4. This new capability (available in APT 2024.5 or higher) further enhances JWST’s ability to perform cutting edge studies of bright, time-variable sources by extending the brightness limit of JWST at wavelengths shorter than 2 µm. For more details, see NIRCam Short Wavelength Grism Time Series and NIRCam Short Wavelength Grism Time Series Observing Strategies. For additional information, please refer to this JWST Observer announcement about this capability.
1 August, 2024 update
JWST Cycle 4 Call for Proposals
The JWST Call for Proposals for Cycle 4 for General Observer (GO) time and Archival Research (AR) has been released. Proposals are due on October 16, 2024 by 8:00pm US Eastern Daylight Time. Please see the Cycle 4 Call for Proposals article for additional dates of interest for Cycle 4.
Cycle 4 proposers should use APT 2024.5 or higher, and ETC 4.0 in proposal preparation.
APT 2024.5 will be released on August 22, 2024. Articles related to this software version will be updated on the same date.
All articles pertaining to JWST Cycle 4 proposal preparation have been reviewed, and most have been revised to reflect the latest on-orbit knowledge and latest proposing tools versions. During the proposing period, these articles will not be modified. However, articles about data calibration and analysis will continue to be updated.
Recent notable updates to articles are listed at the JWST JDox Latest Updates page. In addition, each article has a date stamp at the bottom of the page indicating when significant updates were made to it.
If any changes or updates are deemed necessary by STScI during the Cycle 4 Call for Proposals period, they will be communicated appropriately to the community at large.
20 March, 2024 update
Updates to JWST data products documentation pages
On March 15, 2024, a suite of updates was made to the JWST User Documentation (JDox) pages describing JWST data products. These pages — covering data retrieval, pipeline software, known issues, and data analysis — were significantly restructured to address community feedback and needs.
The best way to navigate this documentation is via the page tree, generally located on the left of the main window. Key areas within the new documentation structure include:
Calibration Status: Descriptions of the current astrometric, photometric, and wavelength calibration accuracy of JWST, broken down by observing mode.
Known Issues with JWST Data: Descriptions of any known issues and artifacts for users to be aware of for each observational mode, along with mode-specific guidance for offline reprocessing and optional steps that may help certain science cases.
Post-Pipeline Data Analysis: Information about available software tools for working with fully-processed science data products.
All of these pages, particularly those concerning ongoing calibration work, will continue to be updated as more information becomes available. In most cases, deprecated pages can still be accessed via saved links, but have banners pointing to the new content location and will be removed in a future update. Users are encouraged to submit a ticket to the JWST Help Desk if they need assistance, have feedback, or encounter a broken link.
News from 2023 and earlier
October 10, 2023
ExoCTK and PandExo updates
The ExoCTK suite of tools has been updated to version 1.2.5. PandExo has also been updated to version 3.0. These releases have been updated for Cycle 3 and both tools are available online. Please see the JWST Observer News article for details.
September 11, 2023 update
Reduced count rate in MIRI imager
The photon count rate and the derived flux of the MIRI imager are lower than what is predicted at wavelengths between 12.8 and 25.5 µm, as mentioned in this news item on August 24, 2023. The current version of the Exposure Time Calculator (ETC) does not include this effect. Users wishing to propose observations for Cycle 3 in filters F560W through F1800W can assume the SNR calculations in the ETC are sufficiently accurate (nominally, the signal-to-noise ratio goes as the square root of the count rate). For the F2100W and F2550W filters, adding margins of 5% on the signal-to-noise ratio to mitigate for the observed loss is strongly recommended.
August 24, 2023 update
ETC 3.0 release
ETC 3.0 is now available for Cycle 3 proposal preparation. It features accuracy updates based on inflight measurements, updates to IFU strategies, and new instrument-specific options for Cycle 3: see the release notes for details, and be sure to review the "Known Issues" summary for this release.
APT2023.5 release
APT 2023.5 is now available for Cycle 3 proposal preparation. Release notes are available at the JWST Helpdesk website (you need to log in to see it listed under "Announcements").
JWST Operational Pipeline build 9.3
A list of all relevant changes to the operational pipeline that was released with build 9.3 and patch build 9.3.1, on August 24, 2023, is available at JWST Operations Pipeline Build 9.3 Release Notes.
Highlights:
The MIRI MRS flux calibration, applied in the photom step of the calwebb_spec2 pipeline, has been upgraded to include corrections for time-dependent changes in throughput.
The jump step in the calwebb_detector1 stage of thepipeline has had several updates and enhancements to make the detection of snowballs/showers more robust and reduce the frequency of "false positives".
The outlier_detection algorithm for IFU data, applied in the calwebb_spec3 stage of the pipeline, has been completely reworked. It now focuses on finding and flagging pixels that are bad in all input images.
The extract_1d step has been upgraded to apply a residual fringe correction to MIRI MRS 1-D extracted spectra.
The photom step in the calwebb_spec2 stage of the pipeline has been updated to calibrate all NIRSpec IFU exposures to units of surface brightness, rather than flux density, for compatibility with the cube_build step's resampling process.
A new pixel_replace step has been added to the calwebb_spec2 stage of the pipeline, to replace the values of bad pixels with estimates from surrounding good neighbors, in order to avoid issues with dropouts in extracted 1-D spectra.
The pointing calculations used in populating WCS keywords in raw ("uncal") products have been updated to fix a bug that was causing large offsets in the WCS for observations that use FGS2 for guiding.
August 15, 2023 update
JWST Cycle 3 Call for Proposals
The JWST Cycle 3 Call for Proposals for General Observer (GO) time has been released. Proposals are due on October 25, 2023 by 8:00pm US Eastern Daylight Time. Please see the Cycle 3 Call for Proposals article for additional dates of interest for Cycle 3.
Cycle 3 proposers should use APT 2023.5 or higher and ETC 3.0 in proposal preparation.
APT 2023.5 and ETC 3.0 will be released on 24 August 2023.
All articles pertaining to JWST Cycle 3 proposal preparation have been reviewed, and many have been revised to reflect the latest on-orbit knowledge and latest proposing tools versions. During the proposing period, these articles will not be modified. However, articles about data calibration and analysis will continue to be updated.
Recent notable updates to articles are listed at the JWST JDox Latest Updates page. In addition, each article has a date stamp at the bottom of the page indicating when significant updates were made to it.
If any changes or updates are deemed necessary by STScI during the Cycle 3 Call for Proposals period, they will be communicated appropriately to the community at large.
August 1, 2023 update
Known issues about JWST data products
A new JDox page provides up-to-date information on Known Issues with JWST Data Products. Designed to address community feedback and needs, this page is organized into separate tables for each instrument mode and a general table for cross-mode issues. For each issue, the table describes the “symptoms” from a user perspective, the underlying cause, a suggested workaround if available, and the plan to mitigate the issue in data products served by MAST. The page is currently in development, and we expect it to include most major issues by the end of August. New items will be added as they are identified and understood.
If you have questions or comments about issues captured or missing from the page, please let us know via the JWST Help Desk.
Lists of all relevant changes to the operational pipeline that was released with build 9.1 and patch build 9.1.1, on February 28, 2023, and patch 9.1.2 on March 15, 2023, are available at JWST Operations Pipeline Build 9.1 Release Notes.
Build 9.1 and patch 9.1.1
Updated the ramp_fitting and some other downstream steps to assign "NaN" to pixels for which a count rate cannot be computed, instead of zero.
Fixed the handling of NIRSpec "leakcal" exposures, including updates to the way they are associated with both target and background exposures in association files, and the way they are subtracted during calwebb_spec2 pipeline processing.
Fixed issues with the computation of the output WCS grid for resampled NIRSpec MOS and fixed slit data.
Fixed bugs in the application of flux calibration to NIRSpec IFU extended source data and the construction of NIRSpec IFU cubes.
Updated the NIRISS SOSS "Algorithme de Traitement des Orders ContAminée" (ATOCA) algorithms used for creating 1-D extracted spectra.
Adjusted the level1b FITS keyword values in science data products for TARG_RA and TARG_DEC to account for proper motion of the target.
Patch 9.1.2
The opencv-python package was added to the pipeline requirements to support the new snowball and shower correction in the jump step, which is now turned on by default.
Fixed an issue causing linked background exposures to not always get associated with their corresponding science exposures.
A list of all relevant changes to the operational pipeline that was released with build 9.1 and patch build 9.1.1, on February 28, 2023, is available at JWST Operations Pipeline Build 9.1 Release Notes.
Highlights:
Updated the ramp_fitting and some other downstream steps to assign "NaN" to pixels for which a count rate cannot be computed, instead of zero.
Fixed the handling of NIRSpec "leakcal" exposures, including updates to the way they are associated with both target and background exposures in association files, and the way they are subtracted during calwebb_spec2 pipeline processing.
Fixed issues with the computation of the output WCS grid for resampled NIRSpec MOS and fixed slit data.
Fixed bugs in the application of flux calibration to NIRSpec IFU extended source data and the construction of NIRSpec IFU cubes.
Updated the NIRISS SOSS "Algorithme de Traitement des Orders ContAminée" (ATOCA) algorithms used for creating 1-D extracted spectra.
December 14, 2022 update
APT Version 2022.7.2 Release
STScI released a new version of APT v2022.7.2 today. Cycle 2 GO/AR proposals must be submitted using APT v2022.7.2. This version includes a patch to create new Cycle 2 proposals from existing proposals, for example declined Cycle 1 General Observer and Director's Discretionary Time proposals. See the Release Notes and Previous APT Releases for more information.
December 6, 2022 update
Delivery and freeze of materials and software supporting the Cycle 2 Call for Proposals
As stated below, the JWST Call for Proposals for Cycle 2 was released on November 15, 2022. As of today, December 6, 2022, all software and documentation in support of the call is available to proposers and will be frozen for the duration of the open call period, which closes at 8 p.m. US Eastern Standard Time on January 27, 2023. The extra time to update the JDox documentation—from November 15, 2022 to today—was granted to STScI in order to provide the most up-to-date information possible in support of Cycle 2 proposing.
This documentation delivery and freeze includes the ETC, APT, the ancillary planning tools (visibility tools, JIST, backgrounds tool, etc.), and JDox itself. As for JDox, all articles have been checked and updated when necessary to include the latest information available to date from in-orbit operations of the observatory and instrumentation. Articles intentionally not updated have been flagged with appropriate banners stating it.
Notable updates made prior to the documentation freeze are listed at the JWST JDox Latest Updates page. In addition, each article has a date stamp at the bottom of the page indicating when significant updates were made to it.
If any changes or updates are deemed necessary by STScI during the freeze period, they will be communicated appropriately to the community at large.
As always, you are encouraged to direct any questions to the JWST Help Desk. Good luck on your Cycle 2 proposals!
We are pleased to announce that the JWST Cycle 2 Call for Proposals for General Observer (GO) time has been released, with up to 5,000 hours available in this cycle.
Proposals are due by 8 p.m. US Eastern Standard Time on January 27, 2023. The Cycle 2 Telescope Allocation Committee will meet in mid-April 2023, with selections announced in May 2023.
APT 2022.7.1, for use with Cycle 2 proposing, will be available to the public as of November 17, 2022. The release date for Exposure Time Calculator for Cycle 2, ETC 2.0, has been set to December 6, 2022. Our documentation system will continue to be updated frequently over the next several weeks, but will be frozen on December 6, 2022, for the remainder of the Cycle 2 open proposal period. You can always check the JDox Latest Updates page to see what has been changed recently.
NASA has announced the establishment of a "zone of avoidance" to help protect the observatory from damage due to micrometeoroids. This zone overlaps a portion of the normal field of regard, thus reducing viewing opportunities for many targets. The intention is to strongly limit the number of observations that need to be scheduled when the observatory is pointing in the avoidance zone. A new JDox article, JWST Micrometeoroid Avoidance Zone, provides more insight into this avoidance region. The Astronomer's Proposal Tool for Cycle 2 proposing (APT 2022.7.1, release date ) includes new features to help users understand their proposed observations in this context and help minimize observations in this region. More information on the APT implementation is available in the article APT Micrometeoroid Avoidance.
Operations with this mode were paused on August 24, 2022 due to excess frictional torque in the grating wheel used for this mode. After careful analysis, a new operational strategy is in place to allow resumed use of this mode. STScI will be in contact with individual affected investigators regarding the re-scheduling of pending MIRI MRS observations.
The NIRSpec instrument model was updated in APT 2022.5.3 and released in mid-September 2022. The instrument model includes the detailed conversion of pixel positions to the sky based on updated astrometric solutions for the instrument. Any observations that use the NIRSpec MSA for target acquisition or for multi-object spectroscopy will be impacted by this update. (Affected users have been contacted directly.)
A problem with NIRSpec nods was also corrected in the APT 2022.5.3 release.
On August 24, 2022, the grating wheel on the MIRI MRS channel experienced excess friction, and NASA has decided to study this situation carefully prior to restarting use of this observing mode. MIRI’s other 3 observing modes—imaging, low-resolution spectroscopy, and coronagraphy—are operating normally and remain available for science observations. Stay tuned for updates when more details become available.
In the APT 2022.5.3 update described above, a fix was applied to the MIRI coronagraphic background "repeat" option that now uses a quadrant opposite to the initial background.
A report on the actual JWST science performance, as characterized through the 6-month commissioning activities, is now available.
The JWST commissioning team has prepared a detailed report describing JWST's science performance as characterized in commissioning. The report provides an excellent summary of the observatory and science instrument performance as it is known at the end of commissioning. Several highlights of most interest to observers include:
Slewing and pointing performance is as good or better than pre-mission expectations and guide star acquisitions are working well. Guiding performance is also excellent, with the pointing stability of the line of sight under fine guidance control several times better than the requirement. See section 2.4 and all of section 3 of the report.
The science instruments are meeting or exceeding their requirements (see section 6 of the report). Overall throughput is generally higher than pre-mission expectations, with up to 30% increased sensitivity for some instrument modes and wavelengths. This has at least 2 ramifications of interest to the user community:
Until full sensitivity details are known from commissioning, which will enable proper updates to the Exposure Time Calculator (ETC) and JWST Interactive Sensitivity Tool (JIST), these tools will generally underpredict actual performance in most cases. Both tools will be updated prior to the Cycle 2 Call for Proposals.
At this time, the JWST Project is not recommending that observers update their programs or their APT files for this effect since the signal-to-noise ratio in observations will usually be higher than predicted. The only exception is for very bright targets that were predicted to saturate in the second group (and that could now, in principle, saturate within the first group). Any programs containing such targets should be carefully reconsidered prior to observation. For questions or concerns, please contact your program coordinator or the JWST Help Desk.
The JWST background levels are a combination of multiple components that vary with time, orientation, wavelength, and observatory conditions. It will take time to fully characterize these components and their variability, and to get the changes into the various planning tools. However, commissioning data are largely consistent with predictions; if anything, near-IR backgrounds may be somewhat lower than expected. See section 5 of the report for details.
In-flight experience has identified a number of artifacts and features that may appear in data, depending on circumstances at the time a given data set was obtained. Some of these effects are seen in data from multiple instruments while others are specific to a given instrument. The Data Features and Artifacts article has pointers to currently available information.
The user community will certainly want to be on the lookout for any of these features in science data and identify them appropriately. If you see anomalies in your data, contact the JWST Help Desk, as ongoing operations can help STScI characterize and possibly mitigate these effects going forward.
Caveats and limitations of the science calibration pipeline
Oct. 4, 2022 update: Because of the dynamic nature of the science calibration pipeline and data processing subsystem, as well as frequent reference file updates early in the mission, early JWST publications should include the CAL_VER, SDP_VER, and CRDS_CTX entries from the relevant data headers so that future researchers can place these results in proper context. For example, an independent researcher may use a version of the data with a later calibration, which may affect a comparison to the earlier data presentation. Given that there are currently 2 servers available for retrieving calibration reference data (CRDS-PUB or CRDS-OPS) and these may provide different versions of the data, publications should also indicate which server was used. See the JWST Calibration Pipeline Caveats article for further details.
The JWST Science Calibration Pipeline software performs nominal processing of JWST data for the many different instruments and instrument modes, making science-ready data products available to users. However, early in the mission, the pipeline software as well as the available calibration reference files are expected to be dynamic, with the scheduling of new software builds as experts implement improvements to the current algorithms or address features and artifacts found during in-flight operations. However, even with these improvements, it is impossible to accommodate certain specialized data processing schemes within the context of a standard pipeline processing system. The bottom line for JWST users is that early data will likely need to be reprocessed as improved information becomes available.
Science data will be reprocessed periodically as new versions of the JWST Science Calibration Pipeline are released and/or as new reference files become available. Use the MAST Portal to subscribe to observations of interest; you will then receive notifications when recalibrated products appear in the Archive for that observation. See the "Program Subscriptions and Notifications" chapter of the MAST Portal Users Guide for information on how to subscribe.
In this release of JDox (on July 12, 2022), STScI is publishing a suite of articles outlining the currently known caveats and limitations of the pipeline products for many of the instrument modes. New articles will be added and the existing articles will be updated as more information becomes available, so check back frequently.
An important point, mentioned above, that bears repeating: due to the dynamic nature of the science calibration pipeline, as well as frequent reference file updates early in the mission, early JWST publications should include the following information:
The CAL_VER and CRDS_CTX entries from the relevant data headers
The server used to retrieve reference files (CRDS-PUB or CRDS-OPS)
This is needed so that future researchers can reproduce results and retrospectively assess calibration issues or the need to recalibrate the data. Please see the JWST Calibration Pipeline Caveats article for more details.
Initial experience with the NIRSpec MOS observing highlights the need for careful vetting of the astrometry derived from pre-imaging against source positions in the Gaia catalog. In particular, the MSA target acquisition procedure has a very limited ability to correct for errors in the initial roll, and so it is essential that the rotation of the reference stars on the sky be aligned with that of the Gaia frame to better than 30” in rotation. Care should be taken to consider any proper motion of the Gaia stars and reference stars to avoid introducing a spurious roll offset larger than this. Early NIRCam pre-imaging observations are included in this requirement until camera distortions are better characterized and included in the NIRCam data processing pipeline. Since this is a dynamic area with ongoing development, it is best to contact your program coordinator and NIRSpec instrument scientist or the JWST Help Desk for more details.
JWST data analysis tool (JDAT) video tutorials now available
All early release observations (ERO) and commissioning data became public during the ERO release on July 12, 2022. Also, as Director's Discretionary Early Release Science program data are obtained (primarily over the first 5 months of science operations), those data will immediately be publicly available. You are encouraged to grab some public data and investigate it!
A number of new videos on the JWST data analysis tools suite (JDAT; Imviz, Specviz, and Cubeviz) are posted at the JWST Observer YouTube channel. A convenient tabular listing with summary descriptions and direct links to each video is now available at Jdaviz Tutorials.
Users may also refer to the videos and support materials from the previous JWebbinar series (open the "Materials and Videos" tab) to get started on working with JWST data.
Looking for JWST data?
Everything you need to get started is available from the Accessing JWST Data article. Don't forget to check the pedigree of existing data in MAST by checking the CRDB context of the calibration files applied to the data set of interest. See the JWST Calibration Pipeline Caveats article (and in particular, the section on CRDS reference file status) for details. Good luck!
Publishing JWST data
As a reminder, please refer to the red box above dated Oct. 4, 2022, for information regarding referencing of the heritage of your data and data processing. When publishing JWST data, please remember to add the appropriate standard acknowledgements, examples of which are shown in MAST. Also, paper authors are obliged to include a digital object identifier (DOI) that points to the data they analyzed. Instructions for doing that can be found in the Special Searches article that is part of the MAST Portal Guide.
Cycle 2 Guaranteed Time Observer call for proposals
JWST Guaranteed Time Observers (GTOs) are invited to submit Cycle 2 GTO science proposals. The details for submitting proposals can be found in the JWST Cycle 2 GTO Call for Proposals, which has just been released.
Notable updates
Cycle 4 Call for Proposals announcement
Update about reorganization of data article
Added item about ExoCTK and PandExo updates
Added item about reduced count rate in MIRI imager
Added information about APT 2023.5, ETC 3.0, and JWST Operational Pipeline build 9.3
Information about the Cycle 3 Call for Proposals
Known issues with JWST data products
Information about JWST Operational Pipeline Build 9.1
Announcement about release of APT v2022.7.2
Announcement of Cycle 2 software and documentation freeze.
Announcement about Cycle 2 Call for Proposals and the micrometeoroid avoidance zone (MAZ)
MIRI MRS resumed operations
JWST PUB CRDS server to be decommissioned
Update on how to express the heritage of data products in publications
Updated information on MIRI MRS and NIRSpec performance
Added pointer to DOI information in the Publication section