THE K2 ECLIPTIC PLANE INPUT CATALOG (EPIC) AND STELLAR CLASSIFICATIONS OF 138,600 TARGETS IN CAMPAIGNS 1–8

By D. Huber, S. Bryson, M. Haas, T. Barclay, G. Barentsen, S. Howell, Sanjib Sharma, D. Stello, S. Thompson. 2015

239 citations recorded by the source corpus.

The K2 Mission uses the Kepler spacecraft to obtain high-precision photometry over ≈80 day campaigns in the ecliptic plane. The Ecliptic Plane Input Catalog (EPIC) provides coordinates, photometry, and kinematics based on a federation of all-sky catalogs to support target selection and target management for the K2 mission. We describe the construction of the EPIC, as well as modifications and shortcomings of the catalog. Kepler magnitudes (Kp) are shown to be accurate to ≈0.1 mag for the Kepler field, and the EPIC is typically complete to Kp ≈ 17 (Kp ≈ 19 for campaigns covered by Sloan Digital Sky Survey). We furthermore classify 138,600 targets in Campaigns 1–8 (≈88% of the full target sample) using colors, proper motions, spectroscopy, parallaxes, and galactic population synthesis models, with typical uncertainties for G-type stars of ≈3% in , ≈0.3 dex in , ≈40% in radius, ≈10% in mass, and ≈40% in distance. Our results show that stars targeted by K2 are dominated by K–M dwarfs (≈41% of all selected targets), F–G dwarfs (≈36%), and K giants (≈21%), consistent with key K2 science programs to search for transiting exoplanets and galactic archeology studies using oscillating red giants. However, we find significant variation of the fraction of cool dwarfs with galactic latitude, indicating a target selection bias due to interstellar reddening and increased contamination by giant stars near the galactic plane. We discuss possible systematic errors in the derived stellar properties, and differences with published classifications for K2 exoplanet host stars. The EPIC is hosted at the Mikulski Archive for Space Telescopes (MAST): http://archive.stsci.edu/k2/epic/search.php.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/346411a0b676c281f5c7a0421806374c47013b50

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In Astronomy and Astrophysics

1. D. Charbonneau
2. E. Gaidos
3. Jon Fortney
4. D. Huber
5. Timothy Morton
6. A. Mann
7. C. Dressing
8. J. Winn

In Instrumentation

1. E. Gaidos
2. D. Charbonneau
3. A. Mann
4. D. Huber
5. Timothy Morton
6. Jon Fortney
7. J. Winn
8. C. Dressing

Citations in the corpus

• The Revised TESS Input Catalog and Candidate Target List (2019, background): “…from broadband photometry (and spectroscopy in a tiny minority of cases) on the basis of a complex set of logic rules, algorithms, and empirical relations (see also Brown et al. 2011; Huber et al. 2016; Berger et al. 2018; Deacon et al. 2019) customized for the TESS bandpass (Stassun et al. 2018).”
• Revised Stellar Properties of Kepler Targets for the Q1-17 (DR25) Transit Detection Run (2016, methodology): “Using the equations (8) and (9) from Huber et al. (2016), we computed the number of subgiants and found that DR25 contains 15,893 subgiants compared to 11,078 in DR24, a 43.5% increase.”
• The Exoplanet Population Observation Simulator. I. The Inner Edges of Planetary Systems (2018, methodology): “After removing giant and sub-giant stars according to the effective temperature dependent surface gravity criterion in Huber et al. (2016), the sample consists of nå=159,238 stars, with a median mass of Må=0.95Me and median radius of Rå=0.94 Re.”
• The GALAH survey: observational overview and Gaia DR1 companion (2016, background): “…have been shown to have uncertainties of up to ∼ 40% for Solar-type stars (e.g., Verner et al. 2011; Everett et al. 2013; Bastien et al. 2014), and similar uncertainties apply for the majority of K2 targets that have been classified in the Ecliptic Plane Input Catalogue (Huber et al. 2016).”
• Revised Radii of Kepler Stars and Planets Using Gaia Data Release 2 (2018, background): “…include broadband colors and proper motions, which efficiently separate dwarfs from Corresponding author: Travis Berger taberger@hawaii.edu giants but cannot resolve intermediate evolutionary states, with typical uncertainties of ≈ 0.3–0.4 dex in log g (Brown et al. 2011; Huber et al. 2016).”
• 197 CANDIDATES AND 104 VALIDATED PLANETS IN K2's FIRST FIVE FIELDS (2016, methodology): “We impose an anti-crowding criterion and remove all targets with a second star in EPIC (complete down to Kp∼ 19 mag; Huber et al. 2016) within 4 arcsec (approximately the Kepler pixel size).”
• Optimized transit detection algorithm to search for periodic transits of small planets (2019, methodology): “Huber et al. (2016) estimate a 1 http://github.com/hippke/tls stellar effective temperature of Teff = 4628 K, a surface gravity of log (g) = 4.6, a stellar mass of Ms = 0.752 M , and a stellar radius of Rs = 0.7 R .”
• The Gaia–Kepler Stellar Properties Catalog. I. Homogeneous Fundamental Properties for 186,301 Kepler Stars (2020, background): “Overall, these ∼ 200,000 target stars either had imprecise stellar parameters – 0.3–0.4 dex uncertainties in log g (Brown et al. 2011; Huber et al. 2016) and ≈ 200 K uncertainties in Teff – or lacked parameters altogether, such as masses, ages, radii, densities, and distances.”