JWST Proposal Categories

General Observer (GO) proposals may be submitted for any amount of observing time on JWST. Proposals may also be submitted to financially support the Archival Research (AR) for the analysis of archival JWST data, to develop data science software to benefit the community of JWST users, or to financially support theoretical research in support of JWST observational programs. 

On this page

Overview of Proposal categories

JWST observations can be requested with a General Observer (GO) Proposal, or through Director's Discretionary (DD) Time Proposals. GO proposal categories include Small, Medium, Large, Calibration, Long-Term, Treasury, and Survey. Funding for JWST-related projects that do not require new JWST observations can be requested with an Archival Research (AR) Proposal. An AR proposal can be either a Regular AR, Calibration AR, Legacy AR, Theory, or a Community Data Science Software Proposal. All GO and AR proposals are peer-reviewed by a Telescope Allocation Committee (TAC), as described in JWST Proposal Selection Procedures. Investigators may request Director's Discretionary (DD) time at any time post-launch for unanticipated and scientifically compelling astronomical observations.



General Observer (GO) Proposals

A GO Proposal may be submitted for any amount of observing time, counted in hours, including all overheads. GO Proposals are classified as Small (≤ 25 hours), Medium (> 25 and < 75 hours) and Large (75 hours). The classification into these categories is the total charged time for the observatory, including overheads. Proposals in these categories can request observing time in future cycles as a Long-Term Proposal when this is scientifically justified, however the program's total time, and hence its category, will be determined from the sum total of time for all cycles in the request. The additional category of Treasury Proposals is designed to stimulate certain types of ambitious and innovative proposals that may not naturally fit into the Small, Medium, or Large Proposal categories.

There are also opportunities to apply for Joint Observing programs to obtain multi-wavelength data, Survey Proposals to designate a set of scheduling-filling observations JWST can make to improve observing efficiency, and Calibration Proposals to provide calibrations for non-standard instrumentation modes. 

Proposers should note that all JWST observations are accepted with the understanding that the timescale on which the observations will actually be obtained will depend on scheduling opportunities and demands on JWST resources. Programs with scheduling constraints may require execution over a period that may extend into the next Cycle.

In general, proposals are either accepted or rejected in their entirety. Accordingly, proposers are urged to request the actual number of hours required to achieve the proposal science goals. Laboratory astrophysics relevant to JWST observations is an acceptable component of a GO proposal. Ground-based observations that complement JWST observations may also be included as a component of a GO proposal, but note that these observations must be obtained independently, as STScI does not award time on ground-based facilities

Small GO Proposals

Small GO Proposals are those that request less than or equal to 25 hours of total time. It is anticipated that approximately 2900 hours will be available for allocation to Small Proposals in Cycle 2. Small Proposals will have a default exclusive access period of 12 months.

Medium GO Proposals

Medium GO Proposals are those that request above 25 hours but less than or equal to 75 hours of total time. The Medium Proposal category exists to ensure that compelling science programs that demand a medium-size hour request have appropriate opportunities for success. It is anticipated that approximately 1250 hours will be available for GO medium proposals in Cycle 2. Medium Proposals will have a default exclusive access period of 12 months.

Large GO Proposals

Large Proposals are those that request more than 75 hours of total time. These programs should lead to a clear advance in our understanding in an important area of astronomy. They must use the unique capabilities of JWST to address scientific questions in a comprehensive approach that is not possible in smaller time allocations. Selection of a Large Proposal for implementation does not rule out acceptance of Small or Medium Proposals to do similar science, but target duplication and overall program balance will be considered.

Approximately 750 hours will be made available to Large and Treasury Proposals in Cycle 2. Data taken for Large Proposals will, by default, have no exclusive access period. Proposals may request an exclusive access period; that request should be justified in the "Special Requirements" section of the proposal and will be subject to TAC review.

Long-Term GO Proposals

Small, Medium, Large, and Treasury GO Proposals may request JWST observing time in more than one cycle if a clear scientific case can be made. Long-Term Proposals must be limited to cases where long-baseline, multi-epoch observations are clearly required to achieve the scientific goals. Long-Term Proposals require a long time baseline, but not necessarily a large number of JWST hours, to achieve their science goals. Examples include astrometric observations or long-term monitoring of variable stars or active galactic nuclei. 

Proposers may request time in up to three cycles (1, 2, and 3). Long-term Proposals should describe the entire requested program and provide a cycle-by-cycle breakdown of the number of hours requested. The review panels and TAC will only be able to award a limited amount of time in future cycles, so a detailed scientific justification for allocating time beyond Cycle 2 must be presented. Scheduling concerns are not a sufficient justification. The sum of all hours requested in Cycles 2, 3, and 4 determines whether a Long-Term Proposal is Small, Medium, or Large, with the appropriate exclusive access periods applied (12 months for Small and Medium, and 0 months for Large). Target-of-Opportunity Proposals are eligible to be Long-Term for rare phenomena if certain conditions are met (see JWST Observation Types). GOs with approved Long-Term Proposals are not required to submit continuation proposals for subsequent cycles.

Treasury GO Proposals

Treasury Proposals are those designed to create JWST datasets of lasting scientific value. A Treasury Program is defined by the following characteristics:

  • The program should focus on the potential to solve multiple scientific problems with a single, coherent dataset. It should enable a variety of compelling scientific investigations.
  • The program should produce data products that are processed or calibrated significantly beyond the capabilities of the JWST Calibration Pipeline to maximize the scientific impact of the program. Examples include tiled images, multi-band object catalogs, or coordinated observations on other facilities (for which some funding can be provided). Funding for the proposed data products will depend on their timely availability. They should be delivered to STScI in suitable digital formats for dissemination via MAST.
  • Data taken under a Treasury Program will usually have no exclusive access period, although brief exclusive access periods may be requested if that will enhance the public data value. Such requests are subject to TAC approval.

The following additional characteristics are particularly encouraged:

  • Development of new techniques for data reduction or analysis.
  • Creation and dissemination of tools (software, Web interfaces, models, etc.), beyond what is offered to the community by STScI, for the scientific community to work with the data products.

The emphasis will be on observations whose value is maximal if taken in the current cycle. However, Treasury Proposals may request observing time to be distributed in future cycles if scientifically required (similar to the situation for Small, Medium, and Large Long-Term GO Proposals). In Cycle 2 approximately 1000 hours of JWST time will be available for Large and Treasury Proposals. Treasury Programs will be selected by the TAC as part of the normal peer review process. Successful proposals will be reviewed by STScI to ensure observing efficiency. Investigators submitting Treasury Proposals must select the Treasury Program flag on the APT cover page and include additional technical details on the scheduling aspects of their program in the “Description of the Observations” section in APT. Note that a proposal can be both Large and Treasury. 

The "Scientific Justification" section of the proposal should include a description of the scientific investigations that will be enabled by the final data products and their importance. The "Technical Justification" section of the proposal should not only include a detailed rationale of the observations, but also plans for data analysis and a description of how the data products will be made available to STScI and the community, the method of dissemination, and a realistic time line.

Calibration GO Proposals

JWST is a complex observatory, with many possible instrument configurations. Calibrations and calibration software are maintained by STScI for the most important and most used configurations. However, STScI does not have the resources to calibrate fully all potential capabilities of all instruments. Additionally, the astronomical community has expressed interest in receiving support to perform calibrations for certain uncalibrated or poorly calibrated modes, or to develop specialized software for certain JWST calibrations. In recognition of this, STScI is encouraging users to submit Calibration Proposals, which aim to fill gaps in the calibration of JWST and its instruments.

Calibration Proposals should not be linked to a specific science program, but should provide a calibration or calibration software that can be used by the community for existing or future programs. A specific science program that has special calibration requirements is not a Calibration Proposal; such a proposal should be submitted as a normal GO Proposal and the necessary calibration observations should be included in the science program. Users submitting Calibration Proposals must contact the appropriate instrument team at STScI (via the helpdesk) to discuss their program prior to submission. Failure to do so will result in automatic rejection of the proposal.

Successful proposers will be required to deliver documentation, data products and/or software to STScI to be made available to the community to support future observing programs or archival research. Funding is available to support Calibration Proposals in the same manner as for normal science programs, with the following exception: Scientists affiliated with STScI are not eligible for any funding to support their role (as PI or Co-I) in a Calibration Proposal.

Calibration Proposals will be reviewed internally at STScI by the Instruments Division. The internal review will provide the TAC with an assessment of the feasibility of the proposal, how the proposal complements/extends the existing calibration program, and the type of science impacted by the proposed calibrations. Proposers should summarize the relevance and overall scientific utility of the calibration techniques and products described in their proposal.

Investigators interested in submitting a Calibration Proposal are encouraged to study the JWST User Documentation to determine the level at which STScI provides calibration and characterization. The data obtained for a GO Calibration Proposal will nominally have no exclusive access period, as is the case for regular calibration observations. Proposers may request an exclusive access period (which should be explained in the "Special Requirements" section of the proposal), but such a request will be subject to panel and TAC review and will only be granted in exceptional circumstances. Calibration Proposals can also be submitted as Survey Proposals or Archival Proposals. AR Proposals are appropriate in cases where the necessary data have already been taken, or for programs that do not require specific data but aim to develop specialized software for certain JWST calibration and data reduction tasks.



Archival Research (AR) Proposals

Observations that are no longer in the exclusive access period are freely available for analysis by scientists through retrieval from the Mikulski Archive for Space Telescopes (MAST). For JWST Cycle 2, this includes all Director's Discretionary Early Release Science datasets, which have no exclusive access period, and some approved GTO program datasets. 

The JWST Archival Research (AR) Program can provide financial support for the analysis of such data sets (as Regular or Legacy AR proposals), or the theory (as AR Theory), or cloud computing (as Cloud Computing Proposals), or science software (as Community Data Science Software Proposals) which maximize their use. There is also an opportunity to support calibration activities (as Calibration AR Proposals) beyond what is produced by the standard calibration pipeline. All AR Proposals must include an analysis plan. Proposals for AR funding are considered at the same time, and by the same reviewers, as proposals for observing time, on the same basis. 

Regular AR Proposals

The general goal of a Regular AR Proposal is to analyze a subset of data from JWST to address a specific scientific issue. In general, the scientific questions addressed should differ from those tackled by the original programs that obtained the data. A strong justification must be given to reanalyze data if the new project has the same science goals as the original proposal. There is no limit to the amount of funding that may be requested in a Regular AR Proposal. For reference, it is expected that the majority of awards will fall under $150,000, with a median of about $75,000. However, STScI actively encourages the submission of more ambitious AR programs for which larger amounts of funding may be justified. Budget plans should be commensurate with the level of work required to carry out the goals of the proposal. Laboratory astrophysics relevant to JWST observations is an acceptable component of an archival proposal.

A Legacy AR Proposal is defined by the following characteristics:

  • The project should perform a homogeneous analysis of a well-defined subset of data from JWST in MAST.
  • The main goal should be to provide a homogeneous set of calibrated data and/or ancillary data products to the scientific community.
  • The results of the project should enable a variety of new and important types of scientific investigations.

We encourage the development of open source community software tools for dissemination to the community.

Legacy AR Proposals

The main difference between a Regular and a Legacy AR Proposal is that the former aims at performing a specific scientific investigation, while the latter will also create data products and/or tools for the benefit of the community. While Legacy AR Proposals will be judged primarily on the basis of scientific merit, the importance and broad applicability of the products produced by the Legacy Proposal will be key features in judging the overall scientific merit of the proposal.

It is a strict requirement for Legacy AR Proposals that the proposed data products be created and distributed to the community in a timely manner. Data products should also be delivered to STScI in a format consistent with the MAST High-Level Science products Contributions Guidelines for dissemination via MAST.

It is anticipated that Legacy AR Proposals will be larger in scope and requested funds than most Regular AR Proposals. While there is no lower limit on the requested amount of funding, it is expected that most Legacy AR Proposals will require at least $150,000, and possibly up to a few times this amount, to accomplish their goals. Commensurate with the expected scope, Legacy AR Proposals are allowed to be multi-year projects, although this is not a requirement. Multi-year projects will be funded on a yearly basis, with continued funding beyond the first year subject to a performance review. Legacy AR Proposals will be evaluated by the TAC in conjunction with Large and Treasury GO Proposals.

The ‘Scientific Justification’ section of the proposal should include a description of the scientific investigations that will be enabled by the final data products, and their importance. The ‘Analysis Plan’ section should describe the plans for data analysis, the data products that will be made available to STScI and the community, the method of dissemination, and a realistic timeline.

Calibration AR Proposals

Calibration Proposals may also be submitted as AR Proposals. AR Proposals are appropriate in cases where the necessary data have already been taken, or for programs that do not require specific data but aim to develop specialized software for certain JWST calibration and data reduction tasks. Users submitting Calibration Proposals must contact the appropriate instrument group (accessible via the JWST Help desk) to discuss their program prior to submission.

AR Theory Proposals

Proposers may request financial support for for theoretical research that is relevant to the JWST mission, and that will have a lasting benefit for current or future observational programs with JWST.

A Theory Proposal should address a topic that is of direct relevance to JWST observational programs, and this relevance should be explained in the proposal. Funding of mission-specific research under the JWST Theory Program will be favored over research that is appropriate for a general theory program, such as the NASA Science Mission Directorate Astrophysics Theory Program. The primary criterion for a Theory Proposal is that the results should enhance the value of JWST observational programs through their broad interpretation (in the context of new models or theories) or by refining the knowledge needed to interpret specific observational results (a calculation of atomic cross sections may fall under the latter category). The results of the theoretical investigation should be made available to the community in a timely fashion.

As with the other AR Proposals, there is no limit to the funding that may be requested in Theory Proposals. For reference, it is expected that the majority of awards will fall under $150,000, with a median of about $75,000. The effort detailed in the Management Plan of the proposal should be commensurate with the level of funding to be requested in the budget submission. Theoretical research should be the primary or sole emphasis of a Theory Proposal. Analysis of archival data may be included, but should not be the main aim of the project. GO or AR Proposals which include a minor component of theoretical research will be funded under the appropriate GO or AR Program. 

A Theory Proposal may be submitted by a non-U.S. PI if there are one or more U.S. Co-Is who request funding. 

Award amounts for Theory Proposals are anticipated to be similar to those made for Regular AR Proposals. STScI also allows the submission of more ambitious proposals for which larger amounts of funding may be justified.

The ‘Scientific Justification’ section of the proposal should describe the proposed theoretical investigation and also its impact on observational investigations with JWST. Review panels will consist of observational and theoretical astronomers with a broad range of scientific expertise. They will not necessarily have specialists in all areas of astrophysics, particularly theory, so the proposals must be written for general audiences of scientists. The ‘Analysis Plan’ section of the proposal should discuss the types of JWST data that will benefit from the proposed investigation, and references to specific data sets in MAST should be given where possible. This section should also describe how the results of the theoretical investigation will be made available to the astronomical community, and on what time-scale the results are expected.

AR Cloud Computing Studies 

All non-exclusive access data for current JWST instruments (MIRI, NIRCam, NIRSpec, NIRISS), will be made available by July 1, 2023 as part of the Amazon Web Services (AWS) public dataset program (aws.amazon.com/public-datasets/). Providing these data in close proximity to AWS faciliates new types of compute-intensive analyses that may have not previously been possible due to individual researcher or research group compute resources. Proposals to make use of this dataset should select the Cloud Computing check box next to the AR category in APT, and be prepared to include a line item in their budget for AWS costs (limit $10,000).

Example use cases for leveraging this data could include: Large scale (re)analyses of data to measure photometric properties or proper motions, computationally-intensive tasks such as training machine learning classifiers, and live community-facing services.

Further reading:

AR Data Science Software Proposals

Proposers have an opportunity under the JWST AR Program to obtain financial support for the development of  software products that will be made available to the community for the purposes of analyzing JWST data. Descriptions of the data products created by the JWST calibration pipeline and related software tools are available on JWST Data Calibration ConsiderationsJWST Science Calibration Pipeline Overview, and JWST Post-Pipeline Data Analysis. Examples of additional products include, but are not restricted to,

  • scripts to mitigate artifacts from specific detectors,
  • tools to identify and extract fluxes/magnitudes from multiple sources within a field,
  • utility software for working with JWST data products, 
  • or codes to produce background-subtracted spectra or software to interact with JWST archive services.

Please contact the Data Science Mission Office (dsmo@stsci.edu) for additional guidance. The primary criterion for a Community Data Science Proposal is that the results should broadly enhance the value of JWST observational products for anyone in the astronomical community. The results of the data science software development should be made available to the community in a timely fashion through an appropriate distribution platform. Open source software using a standard license (https://opensource.org/licenses) is encouraged. The software should have thorough internal documentation at a level consistent with software best practices, and, if computationally intensive, should be compatible with a cloud computing service. 

There is no limit to the amount of funding that may be requested, but it is expected that the amounts will be at a similar level to those in the Regular AR category. The effort detailed in the Management Plan section of the proposal should be commensurate with the level of funding requested. 

A Community Data Science Software Proposal may be submitted by a non-U.S. PI if there are one or more U.S. Co-Is who request funding. 

The ‘Scientific Justification’ section of the proposal should describe the proposed software plan and also its impact on observational investigations with JWST. Review panels will consist of observational and theoretical astronomers with a broad range of scientific expertise. They will not necessarily have specialists in all areas of astrophysics, particularly software development, so the proposals must be written for general audiences of scientists. The ‘Analysis Plan’ section of the proposal should discuss the types of JWST data that will benefit from the proposed investigation, and references to specific data sets in MAST should be given where possible. This section should also describe how the results of the investigation will be made available to the astronomical community, and on what time-scale the results are expected.

Guidelines for AR Proposals

Please consider the following when developing your AR Proposal:

  • In general, any JWST data that you wish to analyze must reside (or be expected to reside) in the Archive, and be released from exclusive access rights by the start of Cycle 2 (July 1, 2023).
  • Programs that require funding for Archival Research and also new observations should be submitted as two separate proposals: one requesting funding for the Archival Research, and the other proposing the new observations. The proposals should refer to each other so that the reviewers will be aware that the proposals are part of the same project.
  • Investigators are allowed to submit an AR Proposal to analyze data that was obtained in a previous GO Program on which they were themselves PI or Co-I, but only if the goals of the AR Proposal differ significantly from those for which GO funding was awarded previously.
  • STScI encourages the submission of AR Proposals that combine JWST data with data from other space-missions or ground-based observatories, especially those data contained in the Mikulski Archive for Space Telescopes (MAST). STScI is an active partner of the Virtual Observatory (VO), and MAST is implementing VO technology to make its data holdings available. In particular, the MAST Data Discovery Portal is available at http://mast.stsci.edu/explore. The Discovery Portal is a one-stop Web interface to access data from all of the MAST supported missions, including HST (in particular the Hubble Legacy Archive- HLA, and Hubble Source Catalog- HSC), TESS, Kepler, GALEX, FUSE, IUE, EUVE, and Swift-UVOT.



Survey Programs

Survey programs are designed to increase the observing efficiency by allowing for short "filler" observations when gaps are identified in the scheduling process. All Survey programs are evaluated together with regular programs in the topical discussion panels, but the requested observing time is drawn from a separate pool. JWST Survey programs are analogous to Snapshot programs on the Hubble Space Telescope.

Survey Proposals are allocated time for observations of targets drawn from a large sample. However, there is no guarantee that any individual target will be observed because the observations are placed on the Long Range Plan after the observing sequence has been determined for standard GO/GTO programs. The number of observations actually executed will depend on the availability of appropriate schedule gaps. In general, only a small proportion of the available targets will be observed. Based on the experience from Cycle 2, we anticipate that up to 200 hours may be available for Survey observations in JWST Cycle 2; the TAC will select programs requesting up to 1000 targets to provide appropriate sky coverage. All accepted Survey programs will terminate at the end of Cycle 2.

PIs are not required to give a complete list of all targets and their coordinates at the time of submission. Example visits should be provided at the time of submission. The program duration listed by APT will be based on those example visits. Both the Abstract and the Scientific Justification must include the total number of targets in the sample and describe their distribution on the sky. Proposers should also describe whether a minimum number of targets is required to reach the science goals. Accepted programs will be required to submit a full target list within one month of the notification of acceptance.

There is no commitment on the part of STScI to obtain any specific completion factor for Survey programs.

Survey programs have the following characteristics:

  • Survey programs may not be used for targets of opportunity.
  • Survey programs may not include moving targets.
  • Observations of any particular target cannot be guaranteed; Survey programs are designed to provide a pool of targets that can be inserted into the observing Proposers are encouraged to submit targets that are well-distributed over the sky to maximize the scheduling opportunities. Targets at high ecliptic latitude are particularly useful since they have longer visibilities.
  • Individual visits are generally expected to have a total duration of less than 90-100 minutes, including the science integration time and all associated overheads. Longer visits are possible but may be more difficult to schedule.
  • Proposers should minimize the data volume for their visits. Guidance on how to achieve low data volumes is given in JDox here.
  • Observations should have minimal constraints to maximize their schedulability.
  • In the case of duplication, Regular GO proposals have priority over Survey Proposals since observation of any specific Survey target is not guaranteed.
  • Proposers may not assign priorities to individual visits in a Survey Targets will be selected for execution based on the available observatory resources.
  • In general, shorter-duration, lower data-volume and spatially well-distributed Survey targets have a higher number of scheduling opportunities and a higher chance of being executed than longer duration, high data-volume and/or spatially clustered Survey observations.
  • Cycle 2 Survey Proposals may only request time in Cycle 2.
  • Calibration Proposals may not be submitted as Survey Proposals.

Survey proposals have a default exclusive access period of 12 months. However, because of the potential benefit to the community at large, proposers should consider seriously the possibility of requesting a shorter access period of 3 or 6 months. While this is not a primary criterion for acceptance or rejection, the reduced period can bring additional benefits to any proposal and will be weighed by the reviewers accordingly (see JWST Cycle 2 Proposal Selection Procedures).



Joint Observing Programs

STScI has reached agreements with several other observing facilities (ALMA, Chandra, HST, NASA-Keck, NOIRLab, XMM-Newton,) to award time for joint programs in which JWST science is the prime science, but multi-wavelength observations from another ancillary observatory are critical for the science goals of the proposal. Joint programs may be for any amount of JWST time. The only criterion above and beyond the usual review criteria is that both sets of data of the same target(s) are required to meet the primary science goals.

Joint JWST-ALMA Observing Proposals

By agreement with Joint ALMA Observatory (JAO), the JWST Telescope Allocation Committee (TAC) will award up to 115 hours of ALMA time on each of the ALMA arrays (12-m, 7-m, and Total Power) to highly ranked proposals that require both JWST and ALMA observations. Similarly, the JAO will be able to award up to 115 hours of JWST time to highly rated proposals awarded ALMA time in its TAC process. The only criterion above and beyond the usual review criteria is that the project must be fundamentally of a multi-wavelength nature, and that both sets of data are required to meet the science goals. Time will only be awarded to joint proposals if both data sets are required for the proposed science. It is not essential that the project requires simultaneous ALMA and JWST observations. ALMA time will only be awarded in conjunction with new JWST observations (and should not be proposed for in conjunction with an AR or Theory Proposal).

Proposals for combined JWST and ALMA observations should be submitted to the observatory with the larger time request (not to both observatories). STScI reserves the right to disallow JWST observations that duplicate those approved via any joint program unless the duplications are justified in the original proposals. 

Joint proposals requesting ALMA time 

  • must comply with the ALMA Users' Policies and Call for Proposals guidelines (https://almascience.org/proposing/learn-more).
  • must request angular resolutions that require array configurations offered in ALMA Cycle 10.
  • can not request ALMA time for VLBI or phased array observing modes. 
  • can not request 50 hours or more of 12-m array time or 150 hours or more of either 7-m or TP array time. (see the ALMA Proposer's Guide for a definition of a Large Program). 

Establishing the technical feasibility of the ALMA observations is the responsibility of the PI, who should review the ALMA Proposer’s Guide or consult with the JAO. A description of the technical information that should be included in the proposal is given in JWST Preparation of the PDF Attachment. For proposals that are approved by JWST, the JAO will perform detailed feasibility checks. The JAO reserves the right to reject any previously JWST-approved observation that proves infeasible, impossible to schedule, and/or dangerous. Any ALMA observations that prove infeasible or impossible could jeopardize the overall science program and may cause revocation of the corresponding JWST observations. Duplicate ALMA observations may also be rejected by the JAO.

Joint JWST-ALMA Proposals must be specified in the ‘Coordinated Telescopes’ section of the proposal with the necessary ALMA hours request. Also, you must include technical information about the ALMA observations in the ‘Coordinated Observations’ section of the proposal.

Joint JWST-Chandra Observing Proposals

By agreement with the Chandra X-ray Center (CXC), the JWST TAC will be able to award up to 300 kiloseconds of Chandra observing time. Similarly the CXC will be able to award up to 150 hours of JWST time to highly rated proposals awarded Chandra time in its TAC process. The only criterion above and beyond the usual review criteria is that the project must be fundamentally of a multi-wavelength nature, and that both sets of data are required to meet the science goals. Time will only be awarded to joint proposals if both data sets are required for the proposed science. It is not essential that the project requires simultaneous Chandra and JWST observations. Chandra time will only be awarded in conjunction with new JWST observations (and should not be proposed for in conjunction with an AR or Theory Proposal). Proposers should take special care in justifying both the scientific and technical reasons for requesting time on both missions.

Of the Chandra observing time that can be awarded in the JWST review, only approximately 15% of the observations may be time-constrained. In addition, only one rapid ToO can be awarded (less than 20 days turn-around time). The minimum expected response time for any  ToO is 24 hours after triggering a Chandra observation.  JWST Cycle 2 proposers should keep their Chandra requests within these limits.

Proposals for combined JWST and Chandra observations should be submitted to the observatory that represents the prime science (not to both observatories). STScI reserves the right to disallow JWST observations that duplicate those approved via any joint program unless the duplications are justified in the original proposals. While there is multi-wavelength expertise in the review panels for both observatories, typically the JWST panels will be stronger in IR science and the Chandra panels in X-ray science.

Establishing the technical feasibility of the Chandra observations is the responsibility of the PI, who should review the Chandra documentation or consult with the CXC. For proposals that are approved by JWST, the CXC will perform detailed feasibility checks in Chandra Cycle 25. The CXC reserves the right to reject any previously JWST-approved observation that proves infeasible, impossible to schedule, and/or dangerous to the Chandra instruments. Any Chandra observations that prove infeasible or impossible could jeopardize the overall science program and may cause revocation of the corresponding JWST observations. Duplicate Chandra observations may also be rejected by the CXC.

Due to increasingly challenging thermal constraints, the amount of Chandra exposure time available for High Ecliptic Latitude (HEL) targets with absolute Galactic latitude > 55 degrees is extremely limited.  If you request joint time on Chandra, please avoid long exposures on such targets if at all possible.  You must note explicitly the requested amount of Chandra HEL time in the body of your science justification.   

Similarly, constraints that may limit the number of days your  targets are observable can be difficult to accommodate within Chandra scheduling.  Chandra calculates this difficulty as Resource Cost (RC).  Only a fixed total number of RC points, as calculated by Chandra’s RC calculator, may be awarded by Chandra's joint partner observatories.  Every proposal requesting joint Chandra time should explicitly list the RC total of their requested Chandra time in the body of the science justification. 

Joint JWST-Chandra Proposals must be specified in the ‘Coordinated Telescopes’ section of the proposal with the necessary CHANDRA kiloseconds request. Also, you must include technical information about the Chandra observations in the ‘Coordinated Observations’ section of the proposal.

Joint JWST-HST Observing Programs

If a science project requires observations with both the Hubble Space Telescope (HST) and JWST, then a single proposal may be submitted to request time on both observatories to the JWST Announcement of Opportunity, so that it is unnecessary to submit proposals to two separate reviews. The proposal should be submitted to the observatory that requires the larger time allocation (where 1 JWST hour is equivalent to 1 HST orbit). Since STScI operates both HST and JWST, the amount of time for JWST-HST Joint Proposals could be revised upwards if the demand is high.

By agreement with the HST Project, the JWST TAC may nominally award 300 orbits of HST observing time. Similarly, the HST TAC may nominally award 150 hours of JWST time. The time will be awarded only for highly ranked proposals that require use of both observatories and shall not apply to Archival or Theory Proposals. The only criterion above and beyond the usual review criteria is that both sets of data of the same target(s) are required to meet the primary science goals. Proposers should take special care in justifying both the scientific and technical reasons for requesting observing time on both missions. It is not essential that the project requires simultaneous HST and JWST observations.

Target of Opportunity observations are allowed. Target of Opportunity (TOO) proposals must state explicitly whether the HST observations require a disruptive ToO (observations within 21 days of notification). No more than one (1) disruptive HST ToO of the joint program will be performed per HST Cycle. Furthermore, Ultra-rapid HST ToO requests (reaction time 2 days or less) will not be accepted for this program; proposals asking for Ultra-rapid HST ToO observations must be submitted in response to the HST Call for Proposals, with HST as the primary observatory. It is mandatory that the PI informs both observatories immediately if the trigger criterion is fulfilled. For this solicitation, no HST time will be allocated without the need for JWST time on the same target to complete the proposed investigation.

Establishing the technical feasibility of the HST observations is the responsibility of the PI, who should review the HST Call for Proposals, Instrument Handbooks, and/or contact the HST Helpdesk. The HST Helpdesk offers new features, to search our documentation and to send your question directly to the appropriate team of experts. Questions may also still be submitted via e-mail to help@stsci.edu. For proposals that are approved by JWST, STScI will perform detailed feasibility checks. STScI reserves the right to reject any previously JWST-approved observation that proves infeasible, impossible to schedule, and/or dangerous to the HST instruments. Any HST observations that prove infeasible or impossible could jeopardize the overall science program and may cause revocation of the corresponding JWST observations. Duplicate HST observations may also be rejected by the STScI.

Joint JWST-HST Proposals must be specified in the ‘Coordinated Telescopes’ section of the proposal with the necessary HST Orbit request. Also, you must include technical information about the HST observations in the ‘Coordinated Observations’ section of the proposal.

Joint JWST-NOIRLab Observing Proposals

By agreement with the National Science Foundation's National Optical-Infrared Astronomy Research Laboratory (NOIRLab), STScI will be able to award time on NOIRLab facilities to highly ranked proposals that request time on both JWST and NOIRLab telescopes. The award of time on NOIRLab facilities will be subject to approval by the NOIRLab Director, after nominal review by the NOIRLab TAC to avoid duplication of programs. Joint JWST/NOIRLab Proposals should be submitted to the observatory that represents the prime science facility (but not both). The important additional criterion for the award of NOIRLab time is that both the JWST and the ground-based data are required to meet the science goals of the project. Time will only be awarded to joint proposals if both data sets are required for the proposed science. It is not essential that the project requires simultaneous NOIRLab and JWST observations. Under this agreement, NOIRLab time will only be awarded in conjunction with new JWST observations (and should not be proposed for in conjunction with an AR or Theory Proposal). Major results from these programs would be credited to NOIRLab and JWST.

NOIRLab has offered up to 5% of its available time to proposals meeting the stated criteria. NOIRLab observing time will be implemented during the NOIRLab observing semesters (2023B for August 2023 to January 2024 and 2024A for February to July 2024). Time cannot be requested for the preceding semester, 2023A. Time may be requested only for those facilities listed on the most recent Call for Proposals webpage. In addition, time on heavily-subscribed resources may be limited by the NOIRLab Director.

Establishing the technical feasibility of the proposed NOIRLab observations is the responsibility of the PI, who should review the NOIRLab documentation or consult with NOIRLab directly. A description of the technical information that should be included in the proposal is given in JWST Preparation of the PDF Attachment. All PIs of joint proposals MUST submit the technical description through the standard NOIRLab process by the nominal March 31, 2023 deadline for semester 2023B. For Gemini proposals, a Gemini PIT proposal must be submitted. For all other telescopes, the standard NOIRLab Time Allocation proposal form must be submitted. Detailed information for Gemini and other telescopes can be found in the Call for Proposals for the 2023B semester. Proposals not received by the March 31, 2023 deadline may not be scheduled for NOIRLab time.

NOIRLab will perform feasibility checks, and reserves the right to reject any approved observation determined to be infeasible, impossible to schedule, and/or dangerous to the telescopes or instruments. Any NOIRLab observations that prove infeasible or impossible could jeopardize the overall science program and may cause revocation of the corresponding JWST time allocation.

Joint JWST-NOIRLab Proposals must be specified in the ‘Coordinated Telescopes’ section of the proposal with the necessary NOIRLab nights request. Also, you must include technical information about the NOIRLab observations in the 'Coordinated Observations' section of the proposal.

Joint JWST-NASA Keck Observing Proposals

By agreement with NASA HQ, the NASA Exoplanet Science Institute (NExScI) and the Space Science Telescope Institute (STScI), the JWST Telescope Allocation Committee (TAC) will award up to 10 - 15 nights of NASA Keck time during observing semesters 2023B (August 1, 2023 - January 31, 2024) and 2024A (February 1, 2024 - July 31, 2024) to highly ranked proposals that request observations from both JWST and NASA Keck. The only criterion above and beyond the usual NASA Keck review criteria is that the project must require both data sets to meet the science goals. It is not essential that the project requires simultaneous NASA Keck and JWST observations. NASA Keck time will only be awarded in conjunction with new JWST observations (and should not be proposed for in conjunction with an AR or Theory Proposal).

Joint proposals for JWST and NASA Keck observations should be submitted to STScI. STScI reserves the right to disallow JWST observations that duplicate those approved via any joint program unless the duplications are justified in the original proposals. 

Joint proposals requesting NASA Keck time:

  • May request observations in the 2023B and/or 2024A semesters. No NASA Keck time awarded to a joint program will be scheduled prior to the start of the 2023B observing semester (August 1, 2023).
  • NASA Keck data collected as part of a Joint Program will have the same Exclusive Access Period (EAP) as the JWST data.
  • Keck observations approved through this joint program will be scheduled in a similar fashion to all other NASA Keck programs. NASA Keck observations lost to weather or instrument/telescope issues will not be rescheduled.
  • Requests for contemporaneous/simultaneous JWST/Keck observations will be considered but cannot be guaranteed.
  • Although teams may propose a similar or the same program to both the NASA Keck and JWST TACs, STScI and NExScI personnel will examine approved programs to avoid duplication of proposals/programs in the use of NASA Keck time.
  • Up to 2 partner Keck Target of Opportunity/cadence interrupts can be awarded by the JWST TAC for the time period covered by the 2023B and 2024A observing semesters.
  • Major results from these programs should be credited to both JWST and NASA Keck.
  • NExScI will not provide funding to successful Joint Program PIs.

Establishing the technical feasibility of the NASA Keck observations is the responsibility of the PI. A description of the technical information that should be included in the proposal is given in  JWST Preparation of the PDF Attachment. NExScI will perform a technical review of the Keck portion of the joint proposals approved by the JWST TAC and reserves the right to reject any approved observation determined to be infeasible, impossible to schedule, and/or dangerous to the telescopes or instruments. Any Keck observations that prove infeasible or impossible could jeopardize the overall science program and may cause revocation of the corresponding JWST time allocation. We, therefore, urge proposers to discuss technical concerns with appropriate staff at both observatories.

Joint JWST-Keck Proposals must be specified in the ‘Coordinated Telescopes’ section of the proposal with the necessary NASA Keck nights request. Technical information about the NASA Keck observations must be included in the ‘Coordinated Observations’ section of the proposal.

Joint JWST/XMM-Newton Observing Proposals

If your science project requires observations from both JWST and the XMM-Newton Observatory, you can submit a single proposal to request time on both observatories to either the JWST Cycle 2 or the XMM-Newton Cycle AO-23 review. Joint JWST/XMM-Newton Proposals should be submitted to the observatory that represents the prime science facility (not to both observatories). 

By agreement with the XMM-Newton Observatory, the JWST TAC may award up to 200 kiloseconds of XMM-Newton observing time. Similarly, the XMM-Newton Observing TAC may award up to 40 hours of JWST time to highly rated proposals. The only criterion above and beyond the usual review criteria is that the project must be fundamentally of a multi-wavelength nature, and that both sets of data are required to meet the science goals. Time will only be awarded to joint proposals if both data sets are required for the proposed science. XMM-Newton time will only be awarded in conjunction with new JWST observations (and should not be proposed for in conjunction with an AR or Theory Proposal). Proposers should take special care in justifying both the scientific and technical reasons for requesting time on both missions.

It is not essential that the project requires simultaneous XMM-Newton and JWST observations. No XMM-Newton observations with a reaction time of less than five working days from the trigger date will be considered. Target of Opportunity (ToO) Proposals must state explicitly whether the JWST observations require a disruptive ToO. No more than one disruptive ToO will be allocated per proposal. It is the responsibility of the PI to inform both observatories immediately if the trigger criterion is fulfilled.

Proposals for combined JWST and XMM observations should be submitted to the observatory that represents the prime science (not to both observatories). STScI reserves the right to disallow JWST observations that duplicate those approved via any joint program unless the duplications are justified in the original proposals. The XMM-Newton AO-23 deadline is nominally in early October 2023. While there is multi-wavelength expertise in the review panels for both observatories, typically the JWST panels will be stronger in IR science and the XMM panels in X-ray science.

Establishing the technical feasibility of the XMM-Newton observations is the responsibility of the PI, who should review the XMM-Newton Instrument Handbooks. All standard observing restrictions for both observatories apply to joint proposals. For proposals that are approved, both projects will perform detailed feasibility checks. Both projects reserve the right to reject any approved observation that is in conflict with safety or schedule constraints, or is otherwise deemed to be non-feasible.

Joint JWST/XMM-Newton Proposals must be identified iin the ‘Coordinated Telescopes’ section of the proposal with the necessary XMM-Newton kiloseconds request. Also, you must include technical information about the XMM-Newton observations in the ‘Coordinated Observations’ section of the proposal.


Next: JWST Observation Types




Latest updates


Originally published