The NASA Exoplanet Archive is the field’s central domain repository: a continuously updated, curated database of confirmed and candidate exoplanets, their host stars, and the mission and survey data behind each detection. Where CASRAI’s existing astronomy pages on SDSS/DESI/Rubin-LSST authorship and ATLAS/CMS/LIGO megacollaboration authorship cover how large surveys and collaborations assign author credit, this guide covers the data infrastructure side of exoplanet research: what the Archive is, what it holds, how it is governed, and how researchers cite and reuse its data.
What the NASA Exoplanet Archive is, and who operates it
The NASA Exoplanet Archive is operated by the California Institute of Technology under contract with NASA, through the NASA Exoplanet Science Institute (NExScI), based at Caltech’s Infrared Processing and Analysis Center (IPAC) in Pasadena, California, in coordination with the Jet Propulsion Laboratory. It functions as an online astronomical exoplanet catalog and data service for the research community, aggregating discovery and characterization data drawn from the peer-reviewed literature and from NASA and partner missions.
In CASRAI’s own domain repository vocabulary, the Archive is a textbook example of a discipline-specific repository: rather than accepting arbitrary deposited files the way a generalist repository does, it curates a single, standardized data model around one research object type — planetary systems and their properties — validated and cross-checked against the published literature before entries are marked “confirmed.”
What data it hosts
The Archive’s holdings fall into a few core categories:
- Confirmed exoplanets — planets published in the peer-reviewed literature and vetted by the Archive’s science team, tracked in the Planetary Systems (PS) and Planetary Systems Composite Parameters (PSCompPars) tables. The confirmed count is a live, continuously growing figure rather than a fixed one; the Archive has passed 6,000 confirmed planets and continues to add new discoveries on an ongoing basis.
- Candidate exoplanets — objects flagged as likely planets by a mission pipeline but not yet independently confirmed, including Kepler Objects of Interest, K2 candidates, and TESS Objects of Interest (TOIs). These are kept in separate, clearly labeled tables from confirmed planets, since the distinction between a validated planet and an unconfirmed candidate is operationally significant for anyone building a research sample from the data.
- Host-star data — stellar parameters (temperature, radius, mass, metallicity, distance, photometry) for the stars each planet orbits, needed to derive planetary properties like radius and equilibrium temperature in the first place.
- Mission and survey data — dedicated tables and pipeline products tied to specific missions and surveys, including Kepler, K2, TESS, JWST, and Pandora, plus ground-based surveys such as SuperWASP and KELT, and detections from microlensing and direct-imaging programs.
Tools and services built around the data
Beyond static tables, the Archive provides interactive tools researchers use directly in the discovery-to-characterization workflow:
- Exoplanet Follow-up Observing Program (ExoFOP) — a shared platform for coordinating and logging follow-up observations of candidates, used heavily by the TESS community.
- Transit and Ephemeris Service — timing predictions for planned transit observations.
- Periodogram Service and EXOFAST — analysis tools for period-finding and for fitting transit/radial-velocity data.
- Table Access Protocol (TAP) and API — programmatic, machine-readable access to every table, letting researchers query and pull data directly into their own analysis pipelines rather than working through the web interface by hand.
The TAP/API layer matters for research data management specifically: it means the Archive functions less like a static download page and more like a live data service that other tools, pipelines, and even other repositories can query directly and keep in sync with.
How researchers use the Archive
In practice, the Archive is used for three overlapping purposes. First, as a target-selection tool — proposing observing time on a telescope for a specific planet or class of planets starts with querying the Archive’s parameters (radius, orbital period, host-star brightness) to build a target list. Second, as a population-level dataset for statistical and demographic studies of exoplanets as a class, where a researcher pulls the full confirmed-planet table (or a filtered subset) rather than any single system. Third, as a literature cross-check, since the Archive’s confirmed-planet entries are tied back to the specific refereed publication that established each parameter, giving a researcher a fast way to trace a given value to its original source.
Data citation and persistent identifiers: the part CASRAI’s audience should not skip
The Archive is a genuinely useful case study in citing a continuously updated dataset correctly, which is a harder problem than citing a fixed data release. Its own guidance distinguishes between:
- Static/versioned tables, which carry their own DOI (issued through NExScI-Caltech/IPAC as publisher) tied to a specific data release — for example, the original Confirmed Planets table (DOI 10.26133/NEA1) was formally retired in 2021 and superseded by the Planetary Systems table (DOI 10.26133/NEA12), each with a distinct persistent identifier rather than one DOI silently pointing at changing content.
- Dynamic, continuously updated tables, where the Archive’s own citation guidance asks authors to additionally record the access date and the number of rows returned by their specific query, since the same table URL can return a different result set a month later as new confirmations are added.
This retire-and-reissue pattern — a new DOI when the underlying data model changes materially, rather than silently redefining what an existing DOI points to — is exactly the discipline CASRAI’s own data repository and trusted digital repository vocabulary describes as good practice for any domain repository serving a live, growing dataset. Researchers citing the Archive should cite the specific table DOI plus the access date and row count for dynamic tables, in addition to the original refereed publication for any individual planet’s discovery.
Its role in the exoplanet data ecosystem
The Archive does not operate in isolation. Raw and calibrated mission data (pixel-level and light-curve products from Kepler, K2, and TESS) live in NASA’s Mikulski Archive for Space Telescopes (MAST), while the Exoplanet Archive sits one layer up: it ingests validated, literature-confirmed parameters and candidate lists derived from that mission data, plus values compiled from the wider published literature, into one standardized, cross-referenced catalog. ExoFOP-TESS, in turn, feeds vetting and follow-up notes back into that pipeline before a TESS Object of Interest is promoted to confirmed status. For a researcher, the practical distinction is: go to MAST for raw pixels and light curves, go to the Exoplanet Archive for curated, publication-ready planet and star parameters.
This is also where the distinction from CASRAI’s existing astronomy content matters. The SDSS/DESI/Rubin-LSST authorship guide and the ATLAS/CMS/LIGO megacollaboration authorship guide answer “who gets listed as an author, and in what order, on a paper produced by a large survey or collaboration.” This guide answers a different question: “where does the underlying planet and star data live, who governs it, and how do I cite it correctly.” A single TESS discovery paper can involve both — a large collaboration author list, and data deposited in and cited from the Exoplanet Archive.
Frequently asked questions
Is the NASA Exoplanet Archive the same as NASA’s Kepler or TESS mission archive?
No. Kepler, K2, and TESS each have their own mission data archived at MAST, which holds the raw and calibrated observational data (images, light curves). The NASA Exoplanet Archive is a separate, higher-level catalog that ingests validated planet and star parameters derived from that mission data and from the wider published literature, rather than the raw observations themselves.
How many confirmed exoplanets does the Archive currently list?
The number changes continuously as new discoveries are confirmed and published; the Archive passed 6,000 confirmed planets and keeps growing. Because the figure is a live count rather than a fixed one, cite the Archive’s own current total (with your access date) rather than a number quoted in a secondary source, which may already be out of date.
Is the data free to access and reuse?
Yes. The Archive is a publicly funded NASA data service, and its tables are freely accessible through the web interface, bulk downloads, and the TAP/API. Individual table DOIs and citation guidance are provided specifically to support proper attribution when the data is reused.
What’s the difference between a confirmed and a candidate exoplanet in the Archive’s tables?
A candidate (such as a Kepler Object of Interest or TESS Object of Interest) is a signal flagged by a mission’s detection pipeline as consistent with a planet but not yet independently validated. A confirmed planet has been vetted and established in the peer-reviewed literature. The Archive keeps these in separate tables specifically so researchers do not accidentally treat an unconfirmed candidate as a validated planet in a downstream analysis.
Does the Archive cover exoplanet host stars, or only the planets themselves?
Both. Host-star parameters (temperature, radius, mass, metallicity, distance) are tracked alongside each planet, because most planetary parameters (radius, equilibrium temperature) are derived relative to the host star and cannot be interpreted without it.
Related CASRAI resources
- Domain repository — the general concept this guide is a worked example of.
- Discipline-specific repository
- How to choose an open data repository
- Research repositories vs. archives
- Desirable characteristics of data repositories (NSTC checklist)
- Astronomy survey authorship: SDSS, DESI, Rubin/LSST
- Megacollaboration authorship: ATLAS, CMS, LIGO
- Research Data Management overview
