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The 2025B NASA Keck Call for Proposals

The Call for Proposals for NASA Keck time in observing semester 2025B (August 1, 2025 to January 31, 2026) is now open.

The opportunity to propose as a Principal Investigator (PI) for NASA time on the Keck Telescopes is open to all U.S.-based astronomers (i.e., those whose principal affiliation is at a U.S. institution).


Important Dates

  • February 13, 2025: NASA Keck Call for Proposals released
  • March 1, 2025: Requests for letters of endorsement for HWO key project due at NASA HQ (Section II.A.)
  • March 13, 2025: All NASA Keck proposals due by 4 pm PDT
  • June 1, 2025: Notification of NASA Keck TAC results
  • August 1, 2025: Start of 2025B observing semester

Application Procedure

The NASA Keck TAC uses a Dual Anonymous Proposal Review (DAPR) process. Proposers prepare two documents: an anonymized Science Program and a non-anonymized Expertise and Access document.


Proposal Submission Site


Highlights for 2025B:

  • In this semester and in future semesters there will be an opportunity to propose for precursor science programs and technology demonstrations relevant to the Habitable Worlds Observatory (Section II.A.).
  • Due to allocations made for Joint JWST-NASA Keck proposals, HWO mission support proposals (Section II.A.), Ariel mission support proposals (Section II.B.), and Key Strategic Mission Support (KSMS) proposals (Section II.C.), there are fewer nights than usual available to NASA Keck proposers. We anticipate that there will be 15-20 nights available to NASA Keck proposers in the 2025B semester.
  • 2025B Semester Notes and Considerations for Keck and Subaru Instruments
  • There are several periods of telescope and instrument unavailability during the 2025B semester which are summarized below. Complete information can be found on the Keck instrument page.

    • Keck I: Keck I will be unavailable for use from August 31 to October 16 for a second planned shutdown to conduct repairs of the telescope pier.
    • KPF and KPF-CC: The KPF Community Cadence (KPF-CC) program is operating a queue observation service in 2025B. PIs who wish to opt in must select the KPF-CC instrument on their WMKO coversheet; the 2025B coversheet will contain both the KPF and KPF-CC instrument options. PIs must also submit all proposed observational requests to the queue prior to the proposal deadline of their TAC. Much more detail on the KPF-CC program, how to opt in, and how to submit requests can be found at this link.
    • Keck II AO: Keck II AO (NIRC2 and NIRSPAO) will be unavailable for three weeks beginning in mid-August.
    • DEIMOS: DEIMOS will be unavailable from October 1 through the end of January for the installation of a new science detector.
    • NIRSPAO and KPIC: NIRSPAO and KPIC will be available through the end of November. NIRSPAO and KPIC will no longer be available for use once SCALES arrives at the Observatory. PIs may apply and be scheduled for NIRSPAO and KPIC time in the December-January timeframe, but must be willing to switch to a backup instrument (NIRSPEC, NIRES, NIRC2-NGS) if SCALES installation is ready to commence during these months. For more information on SCALES, visit this link.
    • KPIC: KPIC Phase I capabilities continue to be offered as a facility instrument in 2025B, during the timeframe that KPIC is available. More information on KPIC Phase I can be found here.
    • Instrument Hibernations: After the receipt of the findings of the Instrument Suite Evolution task force (comprised of members of the WMKO community and WMKO science staff), WMKO, in consultation with the Science Steering Committee, is undergoing a process of hibernation and eventual decommissioning of instruments in the coming years as new capabilities arrive, and to be responsive to pressures on WMKO resources. A hibernated instrument is not available for community use unless there is a significant emergent scientific and strategic need. After a year's hibernation, the hibernated instrument will be completely removed from service and decommissioned. The community should be planning for the following:
      • NIRES: NIRES will be hibernated at the conclusion of the 2025B semester.
      • ESI: ESI will be hibernated at the end of the 2026A semester. ESI will continue to be scheduled in campaign mode to limit the number of reconfigs through each semester.
      • HIRES: HIRES is being considered for hibernation in 2027. A separate communication soliiciting feedback will be sent to the community.
      • Additional instruments are under consideration for hibernation and eventual decommissioning in later semesters, with a focus on those instruments whose capabilities are being significantly superceded by new instrumentation.
    • NIRSPEC/NIRSPAO reconfigs: Please note that NIRSPEC and NIRSPAO/KPIC nights will be scheduled in campaign mode to limit the number of reconfigs into AO during the semester. This may impact the ability to schedule certain date-critical observations.
    • Twilight Cadence Observing: In 2025B, institutions will continue to be able to allocate one twilight observing program per telescope, for a total of up to two programs. On Keck I, OSIRIS-NGS (imager only) will be available, and on Keck II, NIRC2-NGS will be available. Please note that -- due to ongoing AO upgrades -- there will be times in the semester when AO is unavailable for cadence observations. Cadence program PIs are responsible for development of instrument scripts, providing documentation, and training of staff to make the cadence program a turnkey operation.
    • Subaru exchange: The Subaru-Keck exchange will continue as in previous semseters with the number of exchanged nights determined by the demand from each community. Keck will offer LRIS, HIRES, OSIRIS, KPF, and MOSFIRE on Keck I, and DEIMOS, ESI, KCWI, KPIC, NIRSPEC/NIRSPAO, NIRES, and NIRC2 on Keck II. Subaru will offer facility instruments Hyper Suprime-Cam (HSC), HDS, IRCS, MOIRCS, FOCAS, and PFS, as well as visiting instruments IRD, CHARIS + SCExAO, VAMPIRES, REACH, MEC, FastPDI, and NsIR. Note that PIs must contact the instrument PI for visiting instruments in advance, and proposals using the visiting instrumnets/devices must include the relevant PIs as Co-investigators. Subaru may support half-night allocations, but whole-night allocations are preferred.
    • Notes regarding Subaru facility and instrument availability in 2025B:

      • HSC: Queue observing is the default observing mode for HSC; applicants who desire classical mode must jutify their request. Please check the HSC queue mode website for more details.
      • Telescope Downtime: There is a possibility of three weeks of downtime after October for repairs to the dome's main shutter.
      • NsIR Downtime: All instruments except for IRD on the NsIR focus -- including IRCS, SCExAO (CHARIS, VAMPIRES, FastPDI), and REACH -- will be unavailable for ~2-3 months starting in August. After the installation, all IRCS, SCExAO, and REACH observations will be done with the NBS under shared-risk mode. Please see the IRCS and SCExAO webpages for the possible impacts of the NBS.
      • SSP: In S25B, PFS-SSP will be assigned ~10-20 nights over ~3-4 observing runs. IRD-SSP is expected to be completed in S25A.
      • LGS-AO with TBAD: The laser guide star (LGS) system for AO188 will be operated with TBAD (Transponder Based Aircraft Detector) under shared-risk mode.
      • AO upgrade: As part of the AO3k project, the DM has been upgraded from a 188-element bimorph mirror to a 3228-actuator magnetic mirror. AO188 provides three modes: NGS-AO188 mode (uses 188-element WFS + 3k-element DM), LGS-AO188 mode (uses 188-element WFS + 3k-element DM), and NIRWFS-AO3k mode (uses NIR WFS + 3k-element DM). While NIR WFS provides high-performance AO correction, NGS and LGS mode performance is unchanged because they use 188-element WFS. Please refer to the AO188 webpage for more information.
      • Rule for queue/classical mode: HSC/PFS Queue-mode programs should consider a 30% bad weather factor in order to increase the overall observation completion rate, and the requested time for HSC/PFS Queue-mode proposals should not exceed 3.5 nights. It is possible to request up to 5.0 nights in the case of Classical requests.


Useful Links


(last updated February 13th, 2025 16:06:38)

Table of Contents


I. Guidelines for Allocation of NASA Keck Telescope Time

NASA announces this Call for Proposals to use its share of observing time at the W. M. Keck Observatory. This Call is for semester 2025B (August 1, 2025 to January 31, 2026). Allocated nights will be distributed evenly across dark, grey, and bright time. The oversubscription rate is typically ~5:1.

Proposals are due on Thursday, March 13, 2025 at 4 pm PDT and should be submitted via the online submission site. All proposals are required to use these templates for the Science Program (available in Word and LaTex format) and the Expertise and Access document (available in Word and LaTex format).

I.A. Strategic Use of NASA Keck Time

NASA intends the use of its time allocation on the Keck telescopes to be highly strategic in support of on-going missions and/or high priority, long-term science goals as described in the Science Mission Directorate's 2020 Science Plan and in the documents linked below for each science area.

The scientific areas in which proposals are solicited are:

  1. Investigations in support of Exoplanet Exploration (ExEP) science goals and missions to discover and characterize planetary systems and Earth-like planets around nearby stars;
  2. Investigations in support of Cosmic Origins (COR) science goals and missions to study how stars and galaxies came into being;
  3. Investigations in support of Physics of the Cosmos (PCOS) science goals and missions to explore the most extreme physical conditions of the universe, from black holes to dark energy;
  4. Investigations in support of Planetary Science (PS) science goals and missions to study our own solar system.

Within these science areas, two types of proposals for NASA Keck observing time will be accepted:

  1. General observing (GO) time proposals
  2. Mission Support proposals - GO proposals that meet the Mission Support criteria discussed in Section II.

As noted above, in addition to astrophysics investigations, proposers are encouraged to consider compelling planetary science investigations, especially those supported by the recent Planetary Science and Astrobiology Decadal Survey 2023-2032. Proposers should identify how the observations contribute to the body of scientific knowledge needed to help refine objectives of future missions and aid in the understanding of the targeted body. Observations should be of lasting importance to the broad planetary science community.

Proposers should base their science case in terms of strategic relevance toward achieving one or more of NASA's goals in the science areas listed above. Gradations of strategic relevance are listed below. In the "NASA Strategic Relevance" section entered on the submission site, please note and give evidence for the level your program matches. A numerical grade that counts for a significant fraction of the overall grade will be assigned for strategic relevance.

  • This program is critical to support NASA missions or programs, e.g. in support of approved NASA space observations that enable the mission to achieve its Level 1 Requirements such as validation and characterization of transiting exoplanet candidates from Kepler and TESS;
  • This program adds significant value to, or enhances, existing NASA data/missions/facilities by, for example, carrying out a follow-up redshift program for objects detected in deep imaging surveys from HST, Chandra or Spitzer; following up on transient events such as gamma ray bursts or gravitational wave sources detected or localized by SWIFT or Chandra, or validating and characterizing targets important for planning future observations (e.g. JWST target selection), or provides data which directly addresses a NASA strategic goal;
  • This program generically supports NASA's broader science goals.

General Observing and Mission Support programs requiring many nights of Keck time over multiple semesters (up to 4 semesters) may be submitted but must explicitly justify their strategic connection to the stated goals. Read further about multi-semester proposals in Section III.

Within these broad guidelines, the allocation of time will be based on scientific merit, strategic importance, resource availability, and the uniqueness of Keck's capabilities for the investigation. All proposals for NASA Keck time will be evaluated by scientists on the NASA Keck Telescope Allocation Committee (TAC), with the TAC process administered by the NASA Exoplanet Science Institute (NExScI). In recognition of the science communities that NASA Keck time serves, TAC members are selected to ensure balanced expertise in the areas of exoplanets, solar system objects, and in support of NASA's Cosmic Origins and Physics of the Cosmos goals. NASA's proposal solicitation and their evaluation by the NASA Keck TAC are phased to meet the telescope scheduling requirements set by the Director of the Keck Observatory.

I.B. Applying for Observing Time

The opportunity to propose as a Principal Investigator (PI) for the NASA time on the Keck Telescopes is open to all U.S.-based astronomers, i.e. those with their principal affiliation at a U.S. institution. All proposals for NASA Keck time must comply with the criteria outlined in the following sections. The NASA Keck proposal review follows a Dual Anonymous Proposal Review (DAPR) process.

Compliant proposals received by the application deadline will be reviewed and ranked by the NASA Keck TAC. The TAC will submit their recommendations to the selecting official, the NExScI Executive Director, for final selection. NExScI will coordinate the final selections with WMKO for scheduling.

For a complete NASA Keck proposal, PIs will submit the following documents as well as the information requested on the submission site.

  • Anonymized Science Program
  • Non-anonymized Expertise and Access document
  • A PDF of the WMKO Cover Sheet generated through the WMKO Observer Login Page. Please verify that the proposal number on your WMKO cover sheet reflects the current semester and contains an "N" indicating NASA as the allocating institution.
Science Program ( Word template & LaTex template )
  • Science Case: up to 2 pages
  • Anonymized Mission Support justification (if submitting as a Mission Support proposal): up to ½ page
  • Instrument Request: up to 1 page for all proposals
  • Figures and Tables: up to 1 page
  • References: up to 1 page (only for references specific to the anonymous Science Program)
  • List of target stars/objects (Epoch 2000)
Expertise and Access Document ( Word template & LaTex template )
  • Team Expertise: up to 1 page
  • Access to Keck or Subaru Time: up to 1 page
  • Progress Report for Ongoing or Recently Completed Keck Projects AND Status of Allocated Time on Large Telescopes: up to 1 page
  • Request for extension of 12-month period of exclusive use (if applicable): up to ½ page. See criteria for extensions in Section V.
  • References: up to 1 page (only for references specific to the E&A document that are not included in the Science Program references)

Proposals that violate the page limits will be evaluated solely on the information on the allowed pages and will likely receive a lower ranking from the TAC. In extreme cases the proposal will be returned as non-compliant.

Proposers should submit PDFs of their Science Program and Expertise and Access Document using the online proposal submission site which includes fields for:

  • The proposal abstract (the abstract does not need to be repeated in the body of the proposal)
  • A statement on the relevance of the proposed science to NASA's Strategic Goals.
  • A statement why public data in the Keck Observatory Archive are insufficient to meet the science goals of the proposal. See KOA Check section below.

All these fields should be written in DAPR format. Information on the NExScI cover page may be made public for accepted proposals.

Shortly after proposal submission, you will receive an email acknowledgement with attached PDFs of the anonymized and non-anonymized versions of your proposal as received at NExScI. Please email KeckCFP@ipac.caltech.edu if you do not receive the confirmation email or experience problems.

I.B.I. Science Program (Anonymized)

The Science Program should outline the science and technical case for the proposed program using this template available in Word template and LaTex template. These Guidelines for Proposers will assist with writing an anonymized proposal. The scientific case for observing time should establish the following:

  1. The scientific question(s) toward whose solution the observations are requested, and how these questions fit into the larger scientific context;
  2. How the measurements requested will be used to illuminate these questions;
  3. How the proposed science relates to other work in the field, and will advance the field;
  4. How the proposed science fits into NASA's strategic goals as listed above.
  5. If submitting a Mission Support proposal, how the proposed observations meet the criteria described in Section II.D.

The technical case should demonstrate that the proposed measurements are technically feasible, given the performance of the proposed instrument(s), in the time requested.

Specific points that must be addressed include:

  • Why the Keck Observatory and the proposed instruments are essential for the proposed observations
  • The required spatial, spectral, and temporal range and resolution of the proposed observations
  • Estimates of the signal-to-noise required and expected, and justification for the number of nights requested for the entire program, as well as exposure time
  • If requesting less than full nights, indicate which portion of the night is requested (in Hawai'i ST)
  • Cadence/Target of Opportunity justification, if needed
  • Scheduling flexibility/date specific observing and back-up/descope plans, if applicable. Information can be summarized in a table for clarity.
  • If new or unusual techniques are to be used, make clear how observations and calibrations will be obtained
  • Any other information that may assist the TAC in evaluating the scientific merits of the proposal and its suitability for the Keck Telescopes
  • A complete and well-justified target list with sufficient information (magnitudes, coordinates) to determine scheduling within the semester, including which part of the night is requested if asking for less than full nights. Applications without such lists will be rejected. In the case of ToO targets or sources being drawn from on-going surveys (e.g. TESS) or very large samples of sources (e.g. from deep extragalactic fields), a description of the nature and location of the potential targets must be provided in sufficient detail for the TAC to make a thorough review.

The proposal should be aimed at someone who is not a specialist in the particular area of astronomy under study. A specific scientific case with a connection to the bigger picture, rather than a broad general one, is usually more successful with the TAC.

For a proposal to be recommended for scheduling, the proposal must have both a high science and a high strategic grade. The TAC evaluates the scientific merit of each proposal separately from the strategic merit, so successful proposals must present a strong and coherent scientific case.

I.B.II. Expertise and Access Document (Non-anonymized)

As part of the DAPR process, proposers must also submit a non-anonymized Expertise and Access (E&A) document in addition to the anonymized Science Program. The E&A document must use this template available in Word template and LaTex template.

Team Expertise

The one-page team expertise document should demonstrate that the proposal team has the requisite expertise to make the observations and reduce the data in a timely manner. It should include the team's expertise in the following: Keck instrumentation, data reduction and analysis/modeling, and observational experience. For proposals with many Co-Investigators, it is not necessary to report on the qualifications of every team member, only those conducting or leading major aspects of the proposed study. A biography of each team member is not needed.

Access to Keck and Subaru Time

Proposals from PIs, or any Co-Is, who have access to the Keck or Subaru (if applying for Subaru time) telescopes through other partners, specifically the University of California, Caltech, Yale, Keck Observatory, Swinburne, and the University of Hawaii, are accepted by the NASA Keck TAC. However, the Expertise and Access document must specifically include:

  • Why time beyond the allocations available through their institution(s) is required;
  • How access to non-NASA (i.e. institutional) Keck time is being used for the proposed project; i.e. all being used for the proposed project, some being used for the proposed project, none being used for the proposed project;
  • How the program is using any other Keck/Subaru telescope time awarded within the last two years for the proposed project.

The TAC may use access to non-NASA Keck/Subaru time as a factor in determining the final grades and rankings of the proposals. The ability to achieve the science objectives with and without NASA time could be either a positive or a negative factor. If NASA time provides only a small fraction (<< 50%) of the observing time needed to complete a project, the TAC might conclude that NASA time is not crucial for project completion and the proposal may receive a lower ranking in comparison to a project that completes its goals within the NASA allocation. However, if the PI can leverage access to NASA and non-NASA time to address science aligned with NASA's strategic goals that could not be addressed with NASA time alone, the proposal could receive a higher ranking. In the case of two proposals ranked equally on scientific and technical merit, the TAC might use access to additional Keck time as one of the factors in determining the final ranking.

Failure to account for your appropriate level of access to non-NASA Keck time, both on the submission page and in the text of the E&A document, is grounds for proposal rejection.

Progress Report for Ongoing or Recently Completed Keck Projects AND Status of Allocated Time on Large Telescopes

No more than one page should be used to summarize the PI's and key Co-I's current involvement on existing Keck research programs to inform the reviewers of the status of completed and planned observations, data analysis, and publications. A similar summary should be made for other relevant large or space-based telescope time that has been awarded during the past two years.

I.B.III. KOA Check

To use the NASA time on the Keck telescopes as efficiently as possible, proposers must verify, while being DAPR compliant, that their science goals cannot be met through public observations already in the Keck Observatory Archive (KOA). To do this, the PI must enter text into a box on the submission site explaining why data contained in KOA are not sufficient to meet their science goals.

Reasons why additional or different data are needed could be related to, but are not limited to, the cadence, timing, or depth of the archived observations, or the wavelength range or observation mode in which the data were taken. PIs proposing solar system or other target observations that investigate changes over time, can state this without checking the archive. Proposers with large survey programs should describe KOA results for a representative sample of their targets.

To see what data are contained in KOA, please use this link and enter your target list according to the directions.

I.B.IV. HIRES PRV Configuration

HIRES is available in a dedicated precision radial velocity (PRV) configuration. Data collected in this HIRES-PRV configuration are compatible with the public radial velocity pipeline processing environment available at NExScI which will produce wavelength-calibrated 1D spectra and time-series of relative PRVs.

There are important considerations for observers wishing to use the HIRES-PRV configuration; only data collected in the specified HIRES PRV configuration and data collected according to the documented recommendations can be processed properly in the NExScI HIRES processing environment.

I.B.V. Notification and Program Support

Notification

Applicants will be notified of the outcome of the proposal review in early June (B semesters) or early December (A semesters). Successful applicants are encouraged to initiate communications with the WMKO technical staff to ensure that valuable Keck telescope time is used efficiently from your first time on the telescope.

Program Support

Contingent upon funding from NASA Headquarters, PIs of programs assigned time through this Call for Proposals will receive limited research and travel support. Funding awards will be determined through formulaic means. Target of Opportunity and Twilight Observing programs do not receive financial support since the observations may never be triggered.

NExScI will manage the Keck PI Data Awards (KPDAs) and will contract with the Jet Propulsion Laboratory (JPL) to administer the disbursement of most of the funds. Depending on the size of the award and the nature of the PI's home institution, the funding instrument used by JPL will, in most cases, be a Research Support Agreement (RSA). An RSA is a simple Fixed Price, Advance Paid, subcontract provided through JPL that is used for basic research funding where scientific reports and technical data are the only deliverables. RSAs can be awarded to educational and non-profit institutions. Proposals should not include any budget information.

Final Report

The only reporting necessary for KPDAs is a required "end of contract" report outlining the work done and any resulting publications. Please use this final report template to ensure that all relevant information is included. Failure to submit a final report in a timely manner may be grounds for rejection of observing proposals in subsequent years. Final reports should be submitted online.

II. Proposals in Support of NASA Space Missions

In order for a proposal to be considered for Mission Support status, the proposing team must demonstrate in the appropriate section of the anonymized Science Program that the proposed program meets one or more of the programmatic criteria below.

  1. Essential to achieving Level 1 Requirements of the mission, e.g., TESS follow-up essential to validate and characterize planet candidates, or Roman/Euclid calibration of photometric redshifts with spectroscopic redshifts;
  2. Essential to mission planning activities including those affecting the health, safety, and risk mitigation of NASA assets, e.g., in the past, observations looking for potentially harmful debris in the rings orbiting Pluto that might have endangered the New Horizons spacecraft;
  3. Parallel/coordinated observations with NASA assets required for time critical events and/or for independent validation and verification of space mission data, e.g., complementary imaging of solar system objects with JWST;
  4. Longer term mission planning, e.g., in the past, New Horizons was looking for Kuiper Belt objects to fly by after its encounter with Pluto;
  5. Observations essential to the calibration or data reduction of instruments on NASA missions, or that significantly increase the impact of programmatic data from NASA missions.

For any type of mission support proposal to be recommended for scheduling, the proposal must have both a high science and a high strategic grade. The TAC evaluates the scientific merit of each proposal separately from the strategic merit, so successful proposals must present a strong and coherent scientific case.

II.A. Habitable Worlds Observatory (HWO) Precursor Science & Technology Maturation (HWO Sci-Tech) Proposals

Proposals to support maturation of the Habitable Worlds Observatory (HWO) mission concept are solicited starting in semester 2025B. Up to 7 nights per semester will be allocated for: a) new "precursor" science observations that help to close mission architecture trades; and b) projects that mature HWO technologies and/or algorithms using Keck's 10 m segmented telescopes as a testbed. Like other proposals for NASA Keck time, HWO Sci-Tech proposals will be reviewed using a DAPR process. Science proposal topics may address any facet of the mission architecture and are not limited to high-contrast or exoplanet-related observations. The proposals may be for single or multiple semester projects, up to 5 semesters.

To be considered for HWO Sci-Tech status, both science and technology proposals must obtain an endorsement letter from NASA verifying that the proposed project has the potential to significantly affect the mission architecture. Letters may only be obtained by sending an anonymized extended abstract of the proposal 2 weeks in advance of the proposal due date to the Keck Program Scientist Dr. Hashima Hasan. The abstract must include enough detail to allow experts in the HWO Technology Maturation Project Office to assess relevance to HWO. The endorsement letter from NASA HQ must be submitted as part of the proposal through the NExScI submission page. Proposed science projects that do not receive an endorsement letter may be submitted as a regular General Observing proposal.

Science proposals must submit the same documents and information required for General Observing proposals. The Mission Support justification must be replaced with a HWO Relevance justification explaining the relevance of the proposed science to HWO architecture trades. Proposers are encouraged to familiarize themselves with community-driven science gaps germane to HWO that demand new observations, e.g., some of those within this Science Gaps List as well as descriptions of anticipated HWO mission architecture trades, e.g. East et al (2024).

As with the science proposals, the Technology proposals must submit the same documents and information required for General Observing proposals, with the science case replaced with a technical case. The Mission Support justification must be replaced with a HWO Relevance justification explaining the proposed project's relevance for HWO architecture trades and/or technology maturation and its link to the HWO technology, engineering, or modeling gaps (identified by the HWO Chief Technologist here). The Technical Case should clearly identify when the proposed work may be executed, e.g., daytime, bright time, grey time, or dark time. The proposed project must be executable with existing instrumentation or approved near-term hardware upgrades at Keck; no purchases of new hardware may be included as part of the proposal. Proposers must describe the feasibility of implementing their technology maturation project on Keck. Potential benefits to Keck capabilities may be included if applicable. The proposers should estimate what level of hardware or software support, if any, they will need from the Keck engineering staff. Proposals for technology maturation projects will be reviewed by a separate panel of technical experts and evaluated by WMKO to ensure compatibility with observatory operations and safety.

All successful teams will be expected to observe the 12 month exclusive use period for Keck data, unless an exception is made (Section V).

An important element of the HWO mission support program is a plan for timely release of processed data in a form suitable for use by the broader community as a contributed dataset through the Keck Observatory Archive (KOA) or other NASA repository, such as that of the Exoplanet Follow-up Observing Program (ExoFOP). This must include discussion of data products that will result from proposed observing programs, as well as the wider value of these products to the community. The legacy value of the collected data, as well as the compelling data products produced from it, will enable the community to make more and better use of data from NASA space astrophysics and planetary science missions. Therefore, this criterion is an essential part of the HWO Sci-Tech program and has its own section in the Science Program template.

Teams will be required to submit annual reports of progress made, and at the end of the approved proposal period must submit reduced data products, as discussed above. Finally, limited funding may be available to approved programs to support travel to the observatory, data analysis, and other allowed expenses.

II.B. Ariel Mission Support Proposals

As part of the implementation of the NASA Ariel Science Center, NASA-Keck is contributing up to 3 nights per semester for 4 semesters starting in semester 2025B. The time will be allocated through the US Contributions to Ariel Preparatory Science (USCAPS) program and can be allocated across either Keck I or Keck II. Any portion of the 3 nights per semester not allocated by the USCAPS program will remain a part of the general NASA Keck time.

II.C. Key Strategic Mission Support (KSMS) Proposals

KSMS proposals are not solicited for semester 2025B. We anticipate the next KSMS solicitation will take place for the 2026A semester. NASA has solicited proposals for KSMS programs in five previous semesters: 2016A, 2018A, 2019B, 2022A, and 2024A. Abstracts of the KSMS programs selected in these semesters can be read here. The selected proposals directly support the science goals and requirements of NASA missions as well as the legacy value of their data products and are not just larger versions of general science programs.

II.D. General Mission Support Proposals

The NASA Keck TAC accepts General Mission Support proposals every semester. These proposals must demonstrate that the proposed observations provide critical and timely support for confirmed (i.e., at least Phase B) and operating NASA space missions only. In this case, "critical" refers to NASA Keck data meeting one or more of the criteria in Section II above.

The TAC evaluates the science of each Mission Support proposal along with the general proposal pool without special consideration for programmatic impact. However, mission support proposals usually garner high strategic grades, and the NASA Keck selecting official will take the TAC evaluation and programmatic concerns into consideration in making the final time assignments.

III. Multi-Semester Proposals and Applying for Partial Nights

Principal investigators may submit proposals that span up to 4 semesters.

The option of multi-semester proposals reduces the workload on both PIs and the NASA Keck TAC for long-term programs. The NASA Keck TAC will be instructed to address these proposals considering all of the criteria that apply for single semester proposals, in addition to the following:

  • If the proposal were accepted for only a single semester, what is the likelihood that it would be accepted again in ensuing semesters?
  • How much observing time does the TAC consider appropriate to remove from consideration in upcoming semesters?

In considering multi-semester proposals, the TAC may recommend accepting the proposal in its entirety, for some subset of the proposed semesters, or rejecting it outright.

Proposals requesting less than full nights or cadence/Time Domain Astronomy programs must be scientifically and technically justified and can ordinarily be accommodated only if they can be combined with another selected program requiring a compatible instrument and configuration. Observing modes that require substantial observatory support (e.g., Laser Guide Star) are more difficult to schedule as partial night observations.

Programs requesting less than ½ night increments are difficult to schedule and may, in fact, not be schedulable due to the following WMKO requirements: less than ½ night increments must be matched with other compatible NASA programs to fill a full night, and no more than 2 observing programs can be scheduled per night. For example, a ¼ night NASA program must be matched with a compatible ¾ night NASA program.

Please note: Despite the above statement, WMKO anticipates quarter night requests for KPF observations and encourages all Keck I PIs to consider proposing for 0.75 time allocations if this is feasible for their target visibility. Please indicate which portion of the night you are requesting.

The Subaru facility prefers full night allocations, although it is usually possible to arrange half night increments. Please see the special notes for HSC proposals on the Subaru website.

IV. Target of Opportunity, Cadence, and Twilight Observing Proposals

Please read the following policies and the additional details below for NASA Keck time specifically. Subuaru time is not available for these types of observations.

Due to their disruptive nature, ToO or TDA proposals must be of the highest scientific and/or strategic importance. We will try to schedule the highest priority programs but cannot guarantee availability of ToO/TDA observations for all approved programs. Observing modes that require substantial observatory support, e.g. LGS, are more difficult to schedule as ToO observations.

IV.A. Target of Opportunity Proposals

ToO proposals for events likely to happen during a single semester (e.g. gamma-ray bursts, supernovae) must be submitted during the regular submission cycle so that the proposed observations can be considered by the TAC and potential scheduling opportunities can be discussed. ToOs will be limited to instruments currently in use and must be triggered prior to 4 pm HST. All ToO observing teams should set up at-home observing at the beginning of the semester, well ahead of any possible ToO trigger events.

Partner Interrupts vs. Institution (in this case NASA) Interrupts: ToOs can be requested as "Institution" or "Partner." The four major Keck partners (UC, Caltech, UH, and NASA) have agreed that TAC-approved ToO and TDA projects may interrupt observers at any of these four institutions.

The NASA Keck TAC can only allocate up to a total/combination of 6 "Partner" cadence interrupts and ToO triggers per semester; i.e., NASA observers can only interrupt observers from any of the other partner institutions a total of 6 times per semester. Each interrupt cannot exceed 1 hour on a given telescope. Executing ToO interrupts simultaneously on both telescopes is allowed.

Institution interrupts can only be triggered for times when a NASA PI is observing. The limit on the number of institution interrupts is dependent on the number and nature of fractional night NASA programs recommended per semester, and can therefore vary each semester, but will likely be no more than 6.

Under the ToO rules, ALL programs, even partial night programs, are designated interruptible by default. PIs may ask for their time to be designated as uninterruptible, i.e. exempt from ToO or cadence interrupts. To do this, mark the appropriate box on the NExScI submission page and justify in a brief paragraph why the proposed observations cannot be interrupted. This explanation should be strong and scientifically motivated. It is anticipated that interruption-free time will rarely be granted.

Only proposals that fit the case of a ToO observation of an extraordinary opportunity that could not have been anticipated prior to the proposal deadline may be submitted outside of the regular submission cycle to NExScI. Note that all ToO proposals must meet the strategic relevance guidelines described above.

IV.B. Cadence Proposals

NASA observers can also propose for cadence/Time Domain Astronomy (TDA) and Target of Opportunity (ToO) observing programs. ToO proposals for events likely to happen during a single semester (e.g. gamma-ray bursts, supernovae) must be submitted during the regular submission cycle so that the proposed observations can be considered by the TAC and potential scheduling opportunities can be discussed. Cadence/TDA observations are those that can be scheduled in advance and require only a small fraction of a night several times over a semester. Programs requesting date-specific observations should be submitted as 'specific' proposals noting the date restrictions, NOT as cadence proposals.

IV.C. Twilight Observing Proposals

Keck has a program for acquiring snapshot observations during morning twilight. Each partner institution is limited to one twilight program per instrument (currently NIRC2 and OSIRIS) per semester. This program is designed to accommodate extra infrared observations during normally scheduled visible observations, when those observers end early and surrender the last portion of the night. Programs designed for longer term (> 1-2 years) will be given priority.

The guiding principles of the twilight observing program are: 1) on a given night the classically-scheduled PI decides to end their observation early, e.g. due to approaching twilight becoming too bright for a dark time observation; and 2) that the Observing Assistant (OA) agrees to execute the program; twilight observing is completely at the discretion of the classically-scheduled PI and the OA. There is no guarantee on the number of observations that will be conducted. Nevertheless, this program has proven to be advantageous for a certain types of quick snapshot observations.

Furthermore, each approved morning twilight program PI is required to:

  • Use only OSIRIS on Keck I and/or NIRC2-NGS on Keck II
  • Develop target and observation managers
  • Develop, test, and debug instrument scripts
  • Employ only simple instrument configurations
  • Break down the observations into short integrations (< 5min)

Interested PI's should propose using the "cadence" option on the cover sheet. Once a program is approved, the observing team will need to develop a set of instructions, planning tools, instrument scripts for OAs to conduct the observations autonomously.

V. Periods of Exclusive Data Use

Data taken with all instruments on the Keck telescopes are archived in the Keck Observatory Archive (KOA) with the default period of exclusive use determined by each Keck partner institution. As of semester 2023A, the period of exclusive use for NASA Keck data is 12 months. The period of exclusive use for other Keck partners remains at 18 months.

Requests for extensions to the 12-month period of exclusive use will be considered with appropriate personal or professional justification and should be noted on the WMKO cover sheet and included in the Expertise and Access (E&A) document with the reason for the extension meeting one or more of the criteria listed below. Examples of reasonable justifications for an extension include but are not limited to:

  • Data are needed for a soon-to-be completed graduate student thesis (include in the justification the name of the student and advisor, how close the student is to graduating, and the importance of the Keck data to the thesis research);
  • The researcher only has research time outside of the academic year i.e., a professor at a teaching-focused institution;
  • Complex data reduction challenges, including lack of access to a data reduction pipeline;
  • Personal reasons (e.g., parental leave, health-related, etc.);

If an extension of the default exclusive use period beyond the standard 12 months is anticipated at the proposal stage (e.g., for a thesis program), the request should be noted on the cover sheet and included in the Expertise and Access (E&A) document with the reason for the extension. Such requests will not impact the proposal evaluation and selection process.

Six weeks prior to the end of the default exclusive use period, PIs will be alerted that the data are about to go public, and provided with an opportunity to request an extension. Requests for extensions of this 12-month period for NASA Keck data will be considered by the NASA Selecting Official on a case-by-case basis, will require compelling justification, and are unlikely to exceed an additional 6-month period.

Requests for extensions to the period of exclusive use submitted outside the proposal cycle due to unforeseen circumstances will be considered on a case-by-case basis and should be submitted via email.

VI. Publication Acknowledgement

All publications based on data acquired with the Keck telescopes and/or the Keck Observatory Archive must include the acknowledgement(s) below. Please send a citation for any paper using either acknowledgement to NExScI.

VI.A. WMKO and NASA Acknowledgement

"This work was supported by a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute. Data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration through the agency's scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain."

VI.B. KOA Acknowledgement

"This research has made use of the Keck Observatory Archive (KOA), which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute (NExScI), under contract with the National Aeronautics and Space Administration."

Please also use the ADS bibcode provided by KOA to reference the PI of the dataset.

VII. Remote Observing

At home observing: requires the installation of software which only runs on linux and macOS operating systems. First time Keck users of a particular instrument are required to travel to WMKO, if at all possible.

NASA Keck observers have access to the Remote Observing Facility (ROF) at IPAC for their Keck observations. This ROF is located at Caltech/IPAC (Pasadena, CA). See the ROF page for more information and usage guidelines. The procedure to use the IPAC ROF should be started no later than 5 weeks before the scheduled nights, starting with the submittal of a remote observing request through the WMKO observers portal.

Other ROFs are available to NASA users with direct access to these facilities.


(last updated February 13th, 2025 16:06:38)