The TESS Input Catalog and Candidate Target List (1706.00495v6)

Abstract: The Transiting Exoplanet Survey Satellite (TESS) will be conducting a nearly all-sky photometric survey over two years, with a core mission goal to discover small transiting exoplanets orbiting nearby bright stars. It will obtain 30-minute cadence observations of all objects in the TESS fields of view, along with 2-minute cadence observations of 200,000 to 400,000 selected stars. The choice of which stars to observe at the 2-min cadence is driven by the need to detect small transiting planets, which leads to the selection of primarily bright, cool dwarfs. We describe the catalogs assembled and the algorithms used to populate the TESS Input Catalog (TIC). We also describe a ranking system for prioritizing stars according to the smallest transiting planet detectable, and assemble a Candidate Target List (CTL) using that ranking. We discuss additional factors that affect the ability to photometrically detect and dynamically confirm small planets, and we note additional stellar populations of interest that may be added to the final target list. The TIC is available on the STScI MAST server, and an enhanced CTL is available through the Filtergraph data visualization portal system at the URL https://filtergraph.vanderbilt.edu/tess_ctl .

• The paper presents the development of the TIC and CTL as foundational tools for identifying high-priority stars in exoplanet transit studies.
• It integrates cross-matched data from 2MASS, Gaia, and LAMOST to derive accurate stellar parameters and address photometric challenges.
• The CTL employs ranking algorithms to prioritize bright, cool dwarfs, enhancing TESS's ability to detect small Earth-like planets.

The TESS Input Catalog and Candidate Target List

The paper "The TESS Input Catalog and Candidate Target List" outlines the development and structure of the TESS Input Catalog (TIC) and the accompanying Candidate Target List (CTL) to support the Transiting Exoplanet Survey Satellite (TESS) mission. The TESS mission aims to discover small transiting exoplanets orbiting nearby bright stars through a nearly all-sky photometric survey. This essay provides a technical overview of the methodologies and implications of the catalog structures presented in the paper.

The TIC serves as the foundational source catalog for TESS, akin to predecessors like the Kepler Input Catalog (KIC), and is a comprehensive collection of luminous sources covering the entire sky. Critical to TESS's operations, the TIC facilitates target selection for both mission-supported and community-driven observations, including stellar parameter estimations crucial for the transit signal evaluation. The development methodology integrates data from several robust catalogs, including 2MASS for the base framework, supplemented by proper cross-matchings with catalogs such as Gaia DR1, LAMOST, and others, to assemble accurate positional and photometric data.

One pivotal aspect of the TIC efforts is the strategic selection encompassed in the CTL, which distills the TIC's extensive object list down to a set of high-priority stars suitable for TESS's focused 2-minute cadence observations. Qualifying stars, estimated via an assembly algorithm that considers factors such as effective temperature and surface gravity, are primarily bright, cool dwarfs whose properties suggest potential for high-signal, short-period Earth-like planet detection. This catalog depth allows TESS to emphasize stars where the probability of detecting small planetary transits is maximal.

The CTL prioritization takes advantage of signaling noise metrics, such as the estimated photometric precision depending on TESS magnitude and observational coverage by TESS sectors. The use of a ranking scheme that maximizes the detectability of small planets ensures an optimized selection of observational targets. Enhanced features of the CTL such as prioritizing cool, bright dwarfs and a specific highlight of M and sub-dwarf populations aim to address astrophysical interests in planet formation processes around these stellar categories.

An important technical achievement described in the paper is the development of algorithms to derive basic stellar properties such as temperature, mass, and radius from available catalog data, including the manageability of Gaia DR2 data integration in future TIC versions. Additionally, discussions on handling contamination due to blended photometric flux from neighboring stars reflect critical considerations for extracting precise photometric data, emphasizing on the definition of apertures based on simulated TESS point-spread functions.

In terms of scientific and operational implications, this work enables the TESS mission to precisely assay its primary scientific goals, projecting a statistically robust canvas for small planet transits while compensating for stellar variability and observational noise. The strategic optimization allows TESS to fulfill its pivotal role in exoplanetary science, expanding discovery potential around billions of stars and enhancing follow-up characterization of detected planetary bodies. The planned future incorporation of Gaia DR2's rich astrometric data is expected to refine target categorization, particularly enhancing dwarf and subgiant separation.

Overall, the paper provides a detailed account of the extensive cataloging effort foundational to TESS's success, centering around the creation and implementation of the TIC and CTL. As TESS continues its mission, the iterations of these catalogs will reflect advances in astrometric and observational techniques, further solidifying their impact on exoplanet research and astrophysical studies.