Exoplanet Archive Frequently Asked Questions

Q:What happened to NStED and the stellar data it contained?

A: NStED (the NASA Stellar and Exoplanet Database) is no longer supported, but the exoplanet data are still available as part of the NASA Exoplanet Archive. The Exoplanet Archive also contains stellar parameters for exoplanet host stars and a limited number of data sets available for bulk download (see the Bulk Download page).

Searching by stellar parameters for non-planet-hosting stars is no longer available.

Q: Why is the number of planets in the NASA Exoplanet Archive different from the count at the Extrasolar Planet Encyclopedia or exoplanets.org?

A: Each of the exoplanet-related sites have different criteria that are used to include new exoplanets. The NASA Exoplanet Archive includes planets for which the planetary and orbital properties are publicly available, usually through refereed publications. We also restrict our list to those objects whose detection and planetary status is unambiguous. For more information about the archive's criteria for classifying and including planetary objects, see the Exoplanet Criteria page.

Q: When are planets included in the NASA Exoplanet Archive?

A: The list of planets is routinely updated once per week but may be updated more frequently depending on new significant exoplanet discoveries.

Q: How are the pre-generated plots created?

A: The pre-generated plots are produced by using the currently available data within the Exoplanet Archive. Thus, whenever there is an update to the archive information, the plots are re-created to ensure they are as current as possible. This purpose of these plots is to provide to the community fast access to presentation material that describe the current state of the exoplanets field in terms of their number and our understanding of their orbital and physical characteristics.

Q: How can I contribute my data to the archive?

A: The Exoplanet Archive welcomes contributions that meet the guidelines outlined in our documentation.

Q: What happened to the KIC stars which used to be on the false positive list?

A: The objects KOI 68.01 (KepID 8669092), KOI 266.01 (KepID 7375348), KOI 414.01 (KepID 5872150), KOI 948.01 (KepID 9761882), and KOI 1319.01 (KepID 4078157) are no longer considered to be false positives.

Q: What happened to KOI 1902.01 from the candidate list?

A: That object is now considered to be a false positive.

Q: What is a TCE?

A: TCE stands for Threshold Crossing Event and is identified by the Kepler pipeline. A Threshold Crossing Event (TCE) is a sequence of transit-like features in the flux time series of a given target that resembles the signature of a transiting planet to a sufficient degree that the target is passed on for further analysis. For more information, see the Kepler documentation list. The interactive TCE table is available here.

Q: What is a KOI and how is it different from a Kepler Planetary Candidate?

A: KOI stands for Kepler Object of Interest. KOIs are identifed from the list of TCEs for further study. Some KOIs will be classified as false positives, while others will be classified as planetary candidates. Starting with the analysis of quarter 1 to 12 data (Q1-12), the Kepler project is providing the community with the KOI list during the vetting process, so dispositions of a given KOI may change as more information is obtained or more analysis performed. For more information, including a list of all KOI tables, see the Kepler documentation list. The cumulative KOI table is available here.

Q: How are Kepler numbers assigned?

A: Information on the assignment of Kepler numbers to confirmed or validated planets is available on the Kepler Numbers page. A list of all Kepler numbers and their corresponding KOI numbers is available as an interactive table.

Q: Why are values for the KOI planetary radius (orbital period, etc) different between the confirmed planet table and the KOI table?

A: Parameter values in the confirmed planet table come from the published literature, while parameter values in the KOI table come from the Kepler pipeline. Therefore, KOIs which have been published as confirmed or validated planets often have different parameter values in these tables.

Q: Why aren't all confirmed Kepler planets in the KOI table?

A: The KOI table is produced by the Kepler project based on the process described here. Some confirmed planets, for instance the circumbinary planets (such as Kepler 16), were identified outside of the Kepler project or by other means and are not in the KOI table. Confirmed or validated planets in published papers will be included in the confirmed planet table regardless of their status in the KOI table. A list of all Kepler numbers and their corresponding KOI numbers is available as an interactive table.

Q: Can I create a custom transit ephemeris using the Transit Ephemeris Predictor?

A: Yes, it is possible to use your own planet parameters by selecting any existing object from either the Transit and Ephemeris Predictor: All Confirmed Planets or Transit and Ephemeris Predictor: Kepler Objects of Interest tables (click on the corresponding tab within the table interface to view the two data sets). This will take you to a form you can customize by replacing any of the default values.

Q: How do I find all the transiting confirmed planets?

A: To see a list of all transiting planets, use the Planet Transit Flag under Planet Columns in the Confirmed Planet table. All transiting planets will have a value of 1 in this column. Note that some transiting planets were discovered by another method, such as RV, before they were known to transit, so using the Discovery Method column will not provide a complete list.

Q: Some confirmed planets have KOI numbers that are not included in the KOI table. Why is this?

A: Some of these planets have KOIs that were assigned early in the mission when candidates were identified by hand but these candidates are not identified by the pipeline processing which is currently used to generate TCE and KOI lists. Other KOI numbers, particularly those with decimal numbers of 10 and above (e.g. KOI 244.10) are not assigned by the Kepler project and are often used by authors to denote non-transiting planets in Kepler systems with known transiting planets or candidates.

Q: Why can't I find a particular WASP light curve in the archive?

A: The archive currently has data from the first WASP public data release that were acquired from 2004 to 2008. Not all confirmed WASP planet light curves are available in the first public WASP data release, but may be included in future releases.

Q: Why are the stellar parameters listed for some multiple systems different for different planets?

A: The Exoplanet Archive gives the stellar parameters used to derive the planetary parameters. If planets within a multiple system come from different papers (e.g. Kepler-186), then the stellar parameters can vary.

Q: What are default parameters? (Or: Why are some parameters missing in the Confirmed Planets table?)

A: The archive designates a set of default parameters for each planet. This set is drawn from a single published reference to ensure internal consistency (i.e. to avoid having, for example, a planet radius from one paper and an equilibrium temperature from a second paper that might have used a different radius in the derivation). We endeavour to choose the most complete set of parameters available, with a secondary emphasis on drawing parameters from papers comprising multiple data sets, for additional consistency across planets. If the paper with the most complete set of parameters is missing a parameter shown in the table, it will be blank. Users should also note this means the "default" value for a given parameter, may not necessarily be the most precise value published for that parameter. However, values published in other papers can be found by viewing the Overview page for a given planet, where multiple sets of parameters can be displayed. To view a planet's Overview page, click on the blue info icon next to an object name and then click the first link in the pop-up window.

Q: Why do the scroll bars in the interactive tables seem to appear and disappear intermittently?

A: Starting with OS X Lion, Apple changed how scroll bars appear (and disappear) by default, making them fade away when not in active use. This can make it difficult or impossible to scroll in some interfaces, including our interactive tables. This feature is often most noticeable in web browsers, but actually affects multiple programs. To change this behavior, you must change the operating system setting to always show scroll bars.

Q: Why do some objects have very large radii in the KOI table, but much smaller radii in the Confirmed Planets table for the same planet?

A: The planetary parameter values in the KOI table, including the radius, are supplied by the Kepler project from their pipeline and fitting procedures. To maintain a consistently constructed catalog, planetary candidates are not excluded from the KOI table based on their parameter values, even when those values are obviously problematic. The possible issues with these values are discussed in Mullally et al. 2015, particularly Section 7.

In the Confirmed Planets table, values are sourced solely from the peer-reviewed literature. Usually both the planetary and stellar parameter values are different from those provided by the Kepler project, depending on the work done by the team that confirmed or validated the planet.

Q: What is the difference between the KELT and KELT-Praesepe data sets?

A Prior to May 4, 2015, the archive contained a KELT data set that was specifically the Praesepe field, though it was referred to as "KELT" in the archive. We have since released a larger KELT data set, so KELT now refers to the larger data set and the older, smaller data set is referred to as KELT-Praesepe.

Q. Why are there confirmed planets discovered by transit timing variations (TTV) that do not have their TTV flag set?

A: Non-transiting planets discovered via the transit timing variations of another planet in the system will not have their TTV flag set since they do not themselves demonstrate TTVs.

Last update: 12 January 2016