Guest Investigator proposals

The TESS Guest Investigator (GI) program is intended to enable the community to participate in science investigations using TESS. The program enables teams to propose: the collection of new 2-minute and 20-second cadence targets; provides funding to US investigators to analyze 2-minute and 20-second cadence and full-frame image (FFI) data; and provide funding for US investigators to collect ground-based data that supports TESS science. All proposals are managed by the GI office.

The next opportunity is TESS Cycle 4, which begins observations in June 2021 and ends in September 2022, covering observing sectors 40-56. Scientific investigations executed by TESS primarily supported by the TESS GI program. Observations in Cycle 4 will cover the Northern Ecliptic Hemisphere and the Ecliptic Plane.

Cycle 4 fields in Ecliptic coordinates
Cycle 4 fields in Celestial coordinates

There is no exclusive-use data rights to observations collected by TESS. All data is made available through the MAST public archive once data processing and validation is complete.

Important information and useful tools for Cycle 4 proposals are highlighted in the table below.

The Cycle 4 solicitation is now available on NSPIRES.
The Cycle 4 proposal deadline was 4.30pm on January 22, 2021 at 4.30pm EST and is now closed. Proposals are submitted through the ARK/RPS site.
Cycle 4 is longer than a typical cycle and will last approximately 15 months.
Starting Cycle 4, all Phase-1 proposals submitted to the TESS GI program will be evaluated following a dual-anonymous peer review process.
Cycle 4 proposal templates are available. Their use is optional.
The Web TESS Viewing (WTV) tool allows checking of whether a target falls within the TESS field of view, is currently being updated for Cycle 4. The downloadable software, TESS-Point can also be used to check on the observability of targets.
Other useful tools for the planing of observations and the creation of a Phase-1 can be found on our proposal tools page.

Proposal products

  • Approximately 600 20 second cadence target slots per sector are available through the GI program.

  • More than 15,000 target slots are available in each sector for 2-min cadence data per sector, facilitating very large GI programs.

  • Full-frame images are also available, but with a cadence of 10 minutes.

Proposal types

There are three categories of TESS GI proposals for Cycle 4; investigators are free to select the category that best reflects their scope of their proposed work.

  • Mini proposals - This is a new proposal category. These programs require minimal resources, up to 50 20-second cadence targets and 1,000 2-minute cadence targets. Proposals in this category are not eligible for funding.
  • Small proposals - Proposals of limited scope.
  • Large proposals - Proposals of wide-ranging scope and science yield. Large proposals must deliver a clear benefit for the broader scientific community.

Mini proposals are limited to no more than two pages for the science/technical section. Small proposals are restricted to four pages for the science/technical section. Large proposals should be a total of five pages long, where the additional page to the science/technical section is used to describe the benefits that the program will provide to the scientific community. References are not included in the page limits.

No Key projects are solicited in Cycle 4.

Ground-based observation focused projects

Proposals that support the acquisition and analysis of scientific data from ground-based telescopes are solicited. Ground-based observing focused proposals may support the analysis and/or interpretation of TESS scientific data collected in Cycle 4 or TESS data already collected in Cycles 1-3.

Ground-based focused proposals should be identified in ARK/RPS as such and will be reviewed in a panel separately from other proposals submitted to the TESS GI program. All size programs are encouraged, and proposers should identify their program as a Small or Large program. Ground-based observations are not permitted in proposals submitted to the Mini category.

Joint HST, Fermi, and Swift programs

To foster correlative observations, TESS has established joint observing programs with the Hubble Space Telescope (HST), the Fermi Gamma-ray Space Telescope (Fermi), and the Neil Gehrels Swift Observatory (Swift).

Proposals for joint HST observations should be submitted through the HST GO program and the TESS targets will be recommended by that review.

Proposals for joint Fermi observations may be submitted through the Fermi GI program, and the TESS targets will be recommended by that review. Funds for selected programs will be awarded from the Fermi project for joint investigations in this case (and no funds will be awarded from the TESS project). Alternatively, proposals that plan to make use of Fermi data may be submitted to the TESS GI program. TESS GI funding is available to successful U.S.-based investigators who submit a joint TESS-Fermi proposal. If accepted as a TESS proposal no funds will be awarded from Fermi project.

The TESS GI program can also award Swift observations through a joint program with the Swift mission. Observing time under this program will be awarded only to proposals that require use of both observatories to meet the primary science goals. Up to 100 ks Swift time will be available through this program. TESS GI funding is available to successful U.S.-based investigators who request Swift observing time through the TESS GI process. No funds will be awarded from the Swift project for joint investigations proposed to this TESS program element. These proposals will be evaluated on their technical feasibility by members of the Swift team. Proposers should consult the Swift website for information on Swift. Joint programs are not permitted in proposals submitted to the Mini category.

Core science targets

During the extended mission there are no reserved targets or restricted science areas. All scientific investigations using TESS are solicited and relevant to NASA.

Availability of funds

Due to the extended length of Cycle 4 compared to previous cycles, the total amount of funding available to U.S.-based PIs through this solicitation has been increased to $3.4M. TESS 2-minute and 20-second cadence observations are open to all scientists at U.S. or non-U.S. institutions. TESS GI funding is open to all individuals who are identified as Principal Investigators and employed at U.S. institutions.

The dollar amounts assigned to each proposal category are maximum award amounts and are roughly listed below,

  • Small proposals ~ $70,000. (per award)
  • Large proposals ~ $250,000 (per award)

Up to $500,000 will be awarded to ground-based observing focused projects.

Funding for selected programs typically starts upon availability of data to the public archive at MAST. There is no exclusive use period associated with any TESS data.

The performance period of each award will be 1 year; PIs will be allowed to request a no-cost extension for one additional year as needed. The Cycle 4 GI program will also include unfunded non-U.S.-based investigations of high merit, as determined by peer review. Additional Guest Investigation targets will be drawn from proposals in the Mini category and from proposals that are not selected for funding, if target resources permit.

Writing the proposal

The GI office welcomes proposals addressing compelling scientific questions in almost any area of astrophysics and planetary science provided the required observations are amenable to the operational characteristics and constraints of the mission. The science motivation may include, but is not limited to; exoplanet detection and characterization, stellar astrophysics, galactic and extragalactic astrophysics, and solar system science.

The primary purpose of the TESS Guest Investigator Program is to enhance and maximize the science return from TESS. The program facilitates and supports both 2-minute and 20-second cadence observations with TESS and research undertaken with the FFIs. Any area of astrophysics may be proposed.

Proposals may utilize any combination of 2-minute cadence, 20-second cadence, and the full-frame image data. Additionally, proposals that support the acquisition and analysis of scientific data from ground-based telescopes are solicited. All science proposals must be compelling and carefully justified scientifically and technically.

From Cycle 4 onwards all proposals are subject to a dual-anonymous peer review. The aim of a dual-anonymous peer review is to reduce unconscious bias in the evaluation of the merit of a proposal.

Evaluation criteria

When writing a proposal the user should consider the following,

  • The scientific justification of a GI proposal should focus on a compelling investigation that requires the collection of new TESS data or new ground-based data that supports the analysis and/or interpretation of TESS data.
  • The proposed TESS Guest Investigation must clearly enhance the science return of the TESS mission.
  • The proposal may include limited theoretical components, software development and/or data simulation that strengthens the proposal.
    • Proposals must clearly describe the plans to make any new software, higher level data products and/or supporting data publicly available
    • Software developed with TESS GI funds must add value to the TESS science community, be free, and open source.
  • At least 70% of the work effort should be focused on exploiting TESS data products, except in the case of ground-based observing focused proposals.
  • Proposals that are focused on ground-based observing programs must have a clear science driver and describe how the ground-based component is both feasible and required for analysis and/or interpretation of TESS data.
  • Other data products created with TESS GI funding support should be archived as a MAST High-Level Science Product (

In addition proposals submitted in response to the Cycle 4 GI call will be evaluated with respect to the criteria specified in Section C.2 of the NASA Guidebook for Proposers, which are intrinsic merit, relevance to the GI solicitation, and the realism/reasonableness of the proposed work effort and resources. Intrinsic merit includes the following factors:

  • The suitability of using the TESS survey and data products for the proposed investigation (not applicable for ground-based observing focused programs, although ground-based programs should make clear the need for ground-based data in order to analyze or interpret TESS data);
  • The suitability of using the TESS survey and data products for the proposed investigation
  • The degree to which the proposed investigation places demands upon mission resources (this includes justification of the observing cadence requested and the impact on science if a given observing mode is not available during Cycle 4); and
  • The degree to which the proposed investigation capitalizes on the unique capabilities of TESS.

Proposers must take into account the difference between science that can be achieved exclusively using full-frame image data and science that requires new observations at 2-minute and 20-second cadence.

Example proposal templates can be found on the template page.

Investigations focused on the analysis of archival TESS data from Cycles 1, 2 and/or 3, are not compliant with this solicitation and should be submitted to the ROSES-2020 Astrophysics Data Analysis Program (ADAP; D.2) or the Exoplanet Research Program (XRP; E.3).


Application to the TESS GI program is typically open to all investigators, including those from outside the U.S. under NASA's no-exchange-of-funds policy.

Investigators who are not affiliated with a U.S. institution are not eligible for funding through this program, but may submit proposals that will be reviewed and ranked along with eligible proposals for the purpose of allocating targets.

Funding through the NASA TESS GI Program is available only to scientists at U.S. institutions who are identified as the Principal Investigators (PIs). U.S. based Co-Investigators (Co-Is) on foreign-led proposals do not qualify for funding. Funding for accepted target proposals will be initiated only after the relevant observations have begun. Proposers from non-U.S. institutions are strongly encouraged to include a letter of commitment promising financial support.

In accordance with Public Law 113--76, Division B, Title V, Section 532, NASA cannot support bilateral participation, collaboration, or coordination with China or any Chinese-owned company or entity, whether funded or performed under a no-exchange-of-funds arrangement. See Section III(c) of the ROSES-2016 NRA for more information on these restrictions.

The PI of a Phase-1 proposal does not need to be the same as the Phase-2 PI for the budget proposal. A Phase-1 PI is not required to be eligible to hold a grant at their institution. This enables junior scientists to PI Phase-1 proposals.

Target selection

Proposals requesting postage stamp targets are required to submit a target list. Targets must be submitted electronically, at the same time as the science proposal, via the Remote Proposal System (RPS).

Investigators can use the tools listed on the Accessing TESS data products page to aid them in selecting targets. Note the TESS GI program office requires that if a target is in the TIC, GI proposers must provide only the following columns from the TIC in comma separated value (csv) format:

  • TIC ID (if available)
  • Right Ascension (decimal degrees)
  • Declination (decimal degrees)
  • Proper motion in Right Ascension (mas/yr)
  • Proper motion in Declination (mas/yr)
  • TESS mag

additional columns that should be included if necessary are

  • Common name of target
  • Extended flag
  • Special handling flag
  • 20-second cadence flag
  • Swift time request (ksec)
  • Remarks

If a proposed target does not appear in the TIC, the information required to append the target to the TIC must be provided.

Additional tools can be found on our proposal tool and data access pages. We encourage users to follow this custom tutorial provided by the MAST.

We have provided two example target tables with the format we require.

On-source monitoring times

The viewing tool may be consulted to estimate the duration of visibility of targets to be proposed.

Moving targets

Moving aperture targets should be flagged as requiring special handling at proposal submission. Specify in the comments of the target list that this is a moving target. The proposal should discuss in the science case both the minimum and ideal acceptable duration of observations of the target. We will work with the proposal team to generate a delivery format for their targets of interest. Note that this is only necessary if 2-minute/20-second cadence data is requested.

Target of Opportunity Observations

The TESS GI program recognizes the category of Target of Opportunity (ToO) observations of rapidly evolving phenomena whose occurrence is not predictable at the time of the TESS proposal due date. Due to TESS mission constraints, ToO-triggered target definitions can only be uploaded to the spacecraft for the next observing sector. Details regarding the circumstances in which a ToO is triggered must be included in the scientific justification and on the target form. ToO proposals must also include an estimated probability for triggering the observations; the latter will be used in the accounting of total allocated targets. ToOs remain active during the cycle; ToOs not carried out during the cycle must be re-proposed to subsequent solicitations. ToO observations would commence after the spacecraft upload following a trigger. The impact to science of delays between trigger and data collection of several weeks should be addressed in proposals requesting ToO observations. ToO observations are not permitted in proposals submitted to the Mini category.

Submission process

The TESS GI program uses a two-phase proposal process. All proposal materials will be submitted electronically. A Phase-1 proposal shall comprise the science/technical justification; all proposals must include a one-paragraph work plan in the science/technical section except for proposal in the Mini category. This work plan must give details on how the proposed effort will be carried out, including the allocation of effort amongst investigators (expressed in terms of each participant’s role in the investigation to preserve the anonymity of the document)

All proposals requesting funds must also provide upon submission a bottom-line budget number in the provided field of the Astrophysics Research Knowledge-base (ARK) RPS submission form; this number should not be included in the body of the proposal. Only proposers whose Phase-1 proposals are accepted will be invited to submit budget proposals in Phase-2. Proposal content must remain consistent between Phase-1 and Phase-2 proposals. It is not necessary for the PI of the Phase-2 proposal to be the science PI.

The Phase-1 peer review will be performed in a "dual-anonymous" manner, i.e., not only are proposers unaware of the identity of the members on the review panel, but the reviewers do not have explicit knowledge of the proposal teams.

  • All Proposers must submit their Phase-1 proposals electronically through the Astrophysics Research Knowledge-base (ARK)/ Remote Proposal System (RPS) website. If you haven't used ARK/RPS before, we suggest signing up for an account well before the GI proposal deadline; please refer to the ARK/RPS instructions for TESS.

  • You must "verify" the form, and pass the checks, before you can submit your proposal.

  • Target tables for 2-min/20-second cadence observation proposals are to be submitted through ARK/RPS. There are two different ways to provide your target list: into the RPS target form itself, or as a separate CSV file upload - the latter will only become possible after you submit your RPS form. We strongly encourage proposers to submit a CSV file for target lists containing over 100 targets.

  • The Scientific/Technical/Management section of proposals is limited to 2 pages for mini programs, 4 for small programs and 5 pages for large programs, which does not include references. No table of contents in the body of the proposal is required. No supporting material [e.g., curriculum vitae (CV), pending/current support] is required or permitted. An additional page can be used for a target table only.

  • Optional templates for the Scientific/Technical/Management are available.

  • The Scientific/Technical/Management section must be uploaded to the RPS website as a PDF file after you have submitted your RPS proposal form.

  • Proposals from non-U.S. institutions are acceptable and will only be considered on a no-exchange-of-funds basis. Non-U.S. proposals will be reviewed to the same standards as proposals from U.S. institutions and selected solely by NASA.

*All proposals must include a separate "Expertise and Resources - Not Anonymized" document.

All proposal materials must be submitted electronically by 4:30 p.m. Eastern time on the due date for this program given in Section 3 in order to be included in the proposal review for this cycle of the TESS Guest Investigator program. Note that the 4:30 p.m. deadline supersedes the deadline stated in the Guidebook for Proposers and in the ROSES Summary of Solicitation.

NASA uses a single, uniform set of instructions for the submission of ROSES proposals. These instructions are given in the NASA Guidebook for Proposers. TESS GI Proposers should follow these instructions, except where they are overridden by the instructions given in the ROSES Summary of Solicitation.

Specific instructions for dual-anonymous peer review Phase-1 proposals

Cycle 4 will have a dual-anonymous peer review. Under this system the reviewers do not have knowledge of the proposal teams while they perform their scientific evaluation of the proposal.

Proposers should consult the Guidelines for Anonymous Proposals document on the NSPIRES of this program element for instructions on writing proposals appropriate for dual-anonymous peer review. The instructions here and in that document supersede the default instructions given in the NASA Guidebook for Proposers and the ROSES Summary of Solicitation. Proposers will also be required to upload a separate "Expertise and Resources - Not Anonymized" document, which is not anonymized. The "Guidelines for Anonymous Proposals" document contains complete information on how to write this separate document.

AThe key requirements for preparing anonymized Phase-1 proposals are:

  • Anonymization: Phase-1 proposals are anonymized and should eliminate language that identifies the proposers or institutions, as discussed in the Guidelines for Anonymous Proposals. Phase-2 (cost) proposals are not anonymized.
  • Submission: Phase-1 proposals are submitted through ARK/RPS. Phase-2 (cost) proposals are submitted through NSPIRES.
  • References: References should be in the [1], [2] format.
  • Work plan: Include an anonymized one-paragraph work plan in the main body of the Phase-1 proposal.
  • Proposal length: No change.
  • Separate “Expertise and Resources - Not Anonymized” document: This document provides a list of all team members, their roles, expertise, and contributions to the work. The document should also discuss any specific resources that are key to completing the proposed work.

NASA understands that dual-anonymous peer review represents a major shift in the evaluation of General Observer / General Investigator proposals, and as such there may be occasional slips in writing anonymized proposals. However, NASA reserves the right to return without review proposals that are particularly egregious in terms of the identification of the proposing team.

Review process

All proposals are peer-reviewed and ranked by a panel of professional volunteers, followed by ratification from NASA Headquarters. The members of the peer-review panel will not be disclosed. The deliberations of the panel will be disclosed to PIs only after ratification by the selecting official. We anticipate that all proposals focused on ground-based observing will be reviewed by a single panel.

As stated above Cycle 4 will be a dual-anonymous peer review. In order to meet the objectives of dual-anonymous peer review, review panels will be instructed to evaluate the anonymized proposals based on their scientific merit, without initially taking into account the proposing team qualifications. As a final check, and only after the scientific evaluation is finalized for all proposals, the panel will be provided with the "Expertise and Resources - Not Anonymized" documents. The panel will validate the qualifications of the team in order to allow the reviewers to assess the team capabilities required to execute a given proposed science investigation.

NASA recognizes and supports the benefits of having diverse and inclusive scientific, engineering, and technology communities and fully expects that such values will be reflected in the composition of all panels and teams including peer review panels (science, engineering, and technology), proposal teams, science definition teams, and mission and instrument teams.

Submission and evaluation of Phase-2 proposals

Subject to the availability of funding, successful Phase-1 proposers will be contacted by the TESS Program Scientist and invited to submit a budget proposal in Phase-2. Upon notification of selection of a Phase-1 proposal, a proposer must respond as follows:

  • Follow the instructions for submitting a Phase-2 proposal given in the selection notification from the Phase-1 review.
  • Phase-2 proposals must be submitted through the NASA NSPIRES electronic proposal website ( by an Authorized Organizational Representative (AOR) of the proposing organization.
  • The budget proposal will consist of Budget Details (maximum of two pages) section and a Narrative section (maximum of two pages).
  • NASA program personnel will evaluate the Phase-2 cost proposals for cost reasonableness and compare the proposed cost to available funds and consistent with Section VI(a) of the ROSES Summary of Solicitation.

Note that since the Phase-2 proposals will not be peer reviewed, the requirement to redact the budget information (per Section IV(b)(iii) of the Summary of Solicitation) is waived. All costs must be included in the proposal. Proposers should note that Phase-2 (cost) proposals should not be anonymized.