General Information for

NASA Allocated Observing Time on the Keck Telescopes

Proposals for the 2020A observing semester are due Thursday, September 12, 2019 at 4 pm PDT.

Key Dates

Thursday, August 29: deadline to request letters from NASA HQ for General Mission Support proposals.

Thursday, September 12 by 4 pm PDT: deadline for proposal submission.

Highlights for 2020A

  1. Any NASA PI who would like to recover scheduled observing time lost due to the July/August observatory closure should resubmit their proposal written as if the time was lost to weather. The proposal will be evaluated by the TAC, along with the other proposals submitted for the semester, and will not receive any special consideration.

  2. Letters of support for general mission support proposals must be requested from NASA HQ by August 29, two weeks before the submission deadline.

  3. Observers can propose for both Time Domain Astronomy (cadence) and Target of Opportunity (ToO) programs. Programs scheduled in increments of 1/2 nights or smaller are now by default considered interruptible by a ToO, which can last up to 1 hour. Note that ToOs can be requested as "NASA-only" or as "partner interrupts". See Section IV for important details on the number of ToO interrupts allowed each semester.

  4. Twilight Observing: In semester 2019B, the NASA Keck TAC awarded a multisemester program for twilight observing through semseter 2021B. Each partner insitution is limited to one twilight observing program per semester, therefore NASA is not accepting twilight observing proposls for semseter 2020A.

  5. HIRES PRV Configuation: HIRES is available in a dedicated precision radial velocity (PRV) configuration. HIRES data collected in the prescribed HIRES PRV configuration are compatible with the public radial velocity pipeline processing environment available at NExScI. Observers wishing to use the HIRES PRV configuration should read Section Ib.iv and full documentation here.

  6. Special notes and considerations for the Keck instruments for 2020A are available on the WMKO instrument page and include (but are not limited to):

    • Keck 1 LGS will be unavailable from February 1 through mid-April for commissioning of a new laser.

    • OSIRIS-NGS will be unavailable from February 1 to March 15th for installation of the Holographic Aperture Mask.
    • OSIRIS-LGS will be unavailable from February 1 through mid-April, when the K1 laser returns to service.

    • NIRSPEC: Nirspec (Nirspao) will be unavailable from February 1 through mid-March for routine servicing to remove ice from the dewar window, and to address follow up items from last year's upgrade.

    • SUBARU exchange: The SUBARU-KECK exchange will continue as previous semesters with flexibility as to the number of nights available for exchange. The number of exchanged nights will be determined based on the demand from each community. Note that Subaru may support half night allocations, but whole night allocations are preferred. 2020A is the last opportunity to use COMICS since it will be decommissioned soon. Please refer to the WMKO instrument page for complete details.

    Table of Contents

I. Guidelines for Allocation of NASA Keck Telescope Time

NASA announces a call for proposals to use its share of observing time at the W. M. Keck Observatory. This call for semester 2020A (February 1 - July 31, 2020) will allocate 35.5 nights of observing, with planned allocations of 12 nights on Keck 1 and 23.5 nights on Keck 2, distributed evenly across dark, grey, and bright time. Typical over subscription rates range from 3:1 to 5:1.

Proposals are due on Thursday, September 12, 2019 at 4pm PDT and should be submitted via the online submission page. See Section VII for details of the application procedures.

Ia. 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 2014 NASA Science Plan.

The scientific areas in which proposals are solicited are:

  1. Investigations in support of Exoplanet Exploration (ExEP) science goals and missions
  2. Investigations in support of Cosmic Origins (COR) science goals and missions
  3. Investigations in support of Physics of the Cosmos (PCOS) science goals and missions
  4. Investigations of our own Solar System (SS) science goals and missions

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

  1. General Mission Support proposals (see Section IIb )
  2. General observing time proposals

The primary goal of missions within the Exoplanet Exploration Program (ExEP) is to discover and characterize planetary systems and Earth-like planets around nearby stars. Cosmic Origins (COR) Science comprises projects that study how stars and galaxies came into being, how they evolve, and ultimately how they end their lives. Physics of the Cosmos (PCOS) projects explore the most extreme physical conditions of the universe, from black holes to dark energy. PCOS topics include cosmology, high-energy astrophysics and fundamental physics. Solar System (SS) programs involve studies of objects in our own solar system. Proposals may be reassigned to a different science area if deemed appropriate.

Proposers are encouraged to consider compelling planetary science investigations. Many of these objects are possible future mission targets as outlined in the most recent planetary decadal survey. 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 origin or evolution of the targeted body. Observations should be of lasting importance to the broad planetary 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, as described in the 2014 NASA Science Plan. Gradations of strategic relevance are listed below. In the "NASA Strategic Relevance" section on the cover page of your application, please note the level your program matches, and give evidence for how it matches that level; a numberical 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;
  • This program adds significant value to, or enhances, existing NASA data/missions/facilities by, for example, carrying out a redshift survey for objects detected by HST or Spitzer imaging, 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 as described in the NASA Science Plan.

General Observing programs requiring many nights of Keck time over multiple semesters (up to 4 semesters) may be submitted, but must explicitly and strongly justify their strategic connection to the stated goals. Multi-semester proposals are further discussed in Section III below.

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

Ib. Applying for Observing Time

All proposals for NASA Keck time must comply with the following criteria.

Ib.i Science and Technical Case

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

The scientific case for observing time should establish three things:

  1. Outline the scientific question(s) toward whose solution the observations are requested, and place these questions in the larger scientific context.
  2. Show how the measurements requested will be used to illuminate these questions.
  3. Demonstrate how the proposed science fits into NASA's strategic goals for its Keck time as listed above.

The technical case should demonstrate that the proposed measurements are technically feasible, given the performance of the proposed instrument(s), in the time requested, and that the proposal team has the requisite expertise to make the observations and reduce the data in a timely manner. Mission Support proposals must include additional supporting materials as described here.

Specific points that must be addressed include:

  • How the proposed observations relate to the applicant's previous work and to other work in the field.
  • Why the Keck Observatory is essential for the proposed observations.
  • The required spatial, spectral, and temporal range and resolution.
  • Estimates of the signal-to-noise required and expected, and justification for the number of nights requested for the entire program.
  • If new or unusual techniques are to be used, make clear how observations and calibrations will be obtained.
  • A brief description of the status of large telescope time that has been awarded during the past 2 years, such as progress with data reduction and publications.
  • Access to Keck telescopes through other institutions for this or related programs in past 2 years.
  • Any other information that may assist the TAC in evaluating the scientific merits of the proposal and its suitability for the Keck Telescopes.
  • All applications must include 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), 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.

Ib.ii NASA Keck Access

The opportunity to propose as Principal Investigators (PIs) 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.

Proposals from PIs, or any Co-Is, who have access to the Keck telescopes through other partners (the University of California, Caltech, Yale, Keck Observatory, Swinburne, and the University of Hawaii) are required to indicate specifically how they are using any other Keck telescope time they have been awarded within the last two years for the proposed project and why their research requires time beyond the allocations available through their institution(s).

The TAC may use access to non-NASA Keck time as a factor in determining the final grades and rankings of the proposals. For example, 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 to the completion of scientific goals and the proposal may receive a lower ranking in comparison to a proposal which completes its goals within the NASA allocation. However, if the PI can leverage access to NASA and non-NASA time to address science goals 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. Other factors that the TAC may use are listed below in the specific points that proposals must address.

Ib.iii KOA Check

In order to use the NASA time on the Keck telescopes as efficiently as possible, we ask proposers to verify 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 page explaining why the 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 who are proposing solar system or other target observations in order to 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.

Ib.iv HIRES PRV Configuration

HIRES is available in a dedicated precision radial velocity (PRV) configuration. HIRES data collected in this prescribed HIRES-PRV configuration will be 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 several 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 recommendations summarized below can be processed properly in the NExScI HIRES processing environment.

  • The echelle and cross disperser angles must be set at specific angles as part of the HIRES-PRV afternoon setup and must not be changed during the night.
  • A minimum data set per target must be acquired before any PRVs can be determined:
    • A minimum of 3 PRV observations with the iodine cell inserted for a given target are required. The minimum signal-to-noise ratio per pixel for each of these observations must be at least 70 with the optimal SNR being 200.
    • One high SNR (at least 100 per pixel) template observation of the target with the iodine cell removed from the optical path. The optimal SNR for the iodine-out template is 2x the typical iodine-in observation. Several consecutive observations may be stacked to increase the SNR.
    • Each iodine-out template observation must be bracketed by 2-5 exposures of bright, rapidly-rotating B stars with the iodine cell in for calibration. These stars should be as near as possible on the sky to the target star.
  • Individual exposure times should be no longer than 1 hour and iodine-out template observations should span no more than 1.5 hours.
  • Observers new to the HIRES-PRV configuration should treat this configuration as a "new" instrument.

Full documentation of the instrumental setup for the HIRES PRV configuration and the use of the HIRES PRV processing environment can be found here. Questions regarding the HIRES PRV configuration or PRV processing may be directed to Dr. David Ciardi at NExScI.

II. Proposals in Support of NASA Space Missions

IIa. Key Strategic Mission Support (KSMS) Proposals

NASA has solicited proposals for large Key Strategic Mission Support programs in three previous semesters: 2016A, 2018A, and 2019B. Abstracts of the KSMS programs selected in these three semesters can be read here.

The selected proposals directly support NASA mission science goals and are not just larger versions of general science progerams. We anticipate the next call for KSMS projects will be for observing semester 2022A.

IIb. General Mission Support Proposals

The NASA Keck TAC accepts mission support proposals that demonstrate that the proposed observations provide critical and timely support for approved NASA space missions. In this case, "critical" refers to NASA Keck data meeting one or more of the following criteria:

  1. Essential to achieving Level 1 Requirements of the mission, e.g. Kepler follow-up at Keck being essential to validate and characterize planet candidates, validating WISE completeness/reliability right after launch, gathering data during LCROSS lunar impact;
  2. Essential to mission planning activities including those affecting the health, safety, and risk mitigation of NASA assets, e.g. looking for potentially harmful debris in the rings orbiting Pluto that might endanger the New Horizons spacecraft;
  3. Parallel/coordinated observations with NASA assets required for time critical events and/or for independent validation and verification of the space mission data, e.g. to support SOFIA observations of Pluto multiple occultations;
  4. Longer term mission planning, e.g. looking for Kuiper Belt objects that New Horizons might fly to after its encounter with Pluto;
  5. Observations essential to the calibration or data reduction of instruments on NASA missions, e.g. calibration of JWST spectrometers using the spectra of astrophysical objects.

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, the NExScI Executive Director, will take the TAC evaluation and programmatic concerns into consideration in making the final time assignments.

All proposals submitted under the general mission support category must include the following two endorsement letters, either in the proposal package or sent directly to the NASA Keck Operations Scientist, Dr. Dawn Gelino ( by the September 12 due date. Omission of either letter will eliminate a proposal from consideration in the mission support category.

  1. A written endorsement for the current semester from the NASA Headquarters Keck Program Scientist, Dr. Hashima Hasan ( These letters must be requested from NASA Headquarters no fewer than 10 business days before the proposal due date (i.e. by August 29, 2019) and the request must include: the title and abstract of the proposal, the Keck instrument(s) to be used, and a justification for mission support status.
  2. A current, written justification from the flight project, e.g., Project Scientist, Project Manager, or Principal Investigator, which includes an explanation of the criticality, strategic importance, and timeliness of the proposed observations as identified in criteria 1-5 of this section. These letters should be sent to the NASA Keck Operations Scientist, Dr. Dawn Gelino ( with a copy sent to the NASA Headquarters Program Scientist, Dr. Hashima Hasan ( by the September 12 proposal due date.

Since the strong support of your letter writers is critical to deciding whether your proposal meets Mission Support criteria, contact the relevant flight project lead, and Dr. Hasan at NASA HQ, well before the proposal submission deadline.

III. Multi-Semester Proposals and Applying for Partial Nights

Principal investigators may submit general observing/mission support proposals that span up to 4 semesters. This option reduces the workload on both PIs and the NASA Keck TAC for long-term programs. The NASA Keck TAC will be instructed to consider these proposals in light of all of the criteria that apply for single semester proposals, in addition to the following considerations:

  • 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?
  • Does the PI have a demonstrated history of successful proposals?

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

Note that programs requesting less than half night increments are difficult to schedule and may, in fact, not be scheduleable due to WMKO scheduling requirements. These requirements are that less than half night increments be matched with other compatible NASA programs to fill a full night, and that no more than 2 observing programs are scheduled per night. For example, a 1/4 night NASA program must be matched with a compatible 3/4 night NASA program.

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

In semester 2019B, the NASA Keck TAC awarded a multisemester program for twilight observing through semester 2021B. Each partner institution is limited to one twilight program per semester, therefore the NASA Keck TAC is not accepting twilight observing proposals for semester 2020A.

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 classical proposals, not as cadence proposals.

The following policies on ToO and Cadence proposals do not apply to Subaru Exchange time.

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.

Partner Interrupts vs. NASA interrupts: ToOs can be requested as "NASA-only" or "partner." Four 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 allocate up to 6 of these partner interrupts/triggers per semester, i.e. observations that interrupt observers from any of the four institutions. Each interrupt cannot exceed 1 hour.

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

Under the new 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. as 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 Dr. Dawn Gelino. Note that all ToO proposals must meet the strategic relevance guidelines described above.

V. Data Proprietary Periods

Data taken with all instruments on the Keck telescopes are included in the Keck Observatory Archive (KOA) with a default proprietary period of 18 months. Requests for extensions of this default proprietary period MUST be included in the proposal and on the WMKO cover sheet and be scientifically justified. All extensions must be approved by the NASA selecting official.

VI. Publication Acknowledgement

All publications based on data acquired with the Keck telescopes and/or the Keck Observatory Archive should include the acknowledgement(s) below.

Please send a citation for any paper using either acknowledgement to the NASA Keck Operations Scientist, Dr. Dawn Gelino (

WMKO 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 Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain."

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. Application Procedures

To submit your proposal, please follow the guidelines outlined on the Application Procedures page, and submit your proposal via the online submission page. Proposals are due on Thursday, September 12, 2019 by 4 pm PDT.

Proposal Support

Subject to the availability of funds, NASA will financially support PIs of programs assigned time through this call for proposals. PIs will receive limited research and travel support contingent upon NASA Headquarters funding. Funding awards will be determined through formulaic means. Target of Opportunity and twilight observing proposals do not receive financial support since the observations may never be triggered. PIs of approved KSMS programs are expected to be awarded up to $75K/year depending on the number of nights the program is awarded and the complexity of the proposed final data products.

NExScI will manage the Keck PI Data Awards 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. JPL is unable to issue grants. Proposers should not include any budget information in the proposal however successful KSMS proposers will be contacted by NASA Headquarters for detailed budget information.

The only reporting necessary for KPDAs is a final "end of contract" report outlining the work done and listing publications from the research. This report is required. 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 can be submitted online.

VIII. Remote Observing

NASA Keck observers have direct access to three Remote Observing Facilities (ROFs) for their Keck observations. These ROFs are located at Caltech (Pasadena, CA), Yale University (New Haven, CT) and USRA (Columbia, MD). See the ROF page for more information and usage guidelines. The procedure to use one of these ROFs should be started no later than 5 weeks before the scheduled nights.

Note that other ROFs are available to NASA users with direct access to these facilities.

Web Curator and NExScI Cognizant Official: Dr. Dawn Gelino

(last updated August 13th, 2019 14:44:51)