Data Columns in the Kepler Astrophysical False Positive Probabilities Table

The False Positive Probabilities interactive table contains the results of running an automated transit false-positive-probability (FPP) calculating procedure on all KOIs. This procedure was first documented in Morton (2012) and has evolved slightly since then, with the most current description being in Montet et al. (2015).  The code used to implement this procedure is the Python module vespa, which is freely available online at https://github.com/timothydmorton/vespa. After the completion of this work, the vespa code was further improved and the false-positive probabilities recomputed in preparation for publication; the updated results can be found in Morton et al. 2016.

A key part of these calculations involves estimating the posterior probability distributions of the physical parameters of the transit host stars, which are modeled as single, binary, and triple systems and constrained by both broad-band photometry and spectroscopy (when available). The vespa code uses the isochrones module to accomplish this, and the summary results of the single-star fits are presented in this table alongside the FPP results. 

These FPP calculations represent an additional level of analysis that might help determine which KOIs are planets and which are false positives. The results of this analysis have not yet been incorporated into any of the other Kepler data products. Consequently, they have not influenced the robovetter dispositions provided in the Q1-Q17 DR24 KOI table (Coughlin et al. 2015) or the autovetter dispositions provided in the Q1-Q17 DR24 TCE table (Catanzarite et al., 2015). Hence, these results could address the reliability of these catalogs by identifying residual false positives. Of course, it is also possible that one of the key assumptions of the FPP calculation is violated (e.g., the "exclusion radius" inside of which a blended eclipsing binary false positive might live could be underestimated) or the transit signature is an instrumental artifact that is not properly modeled by this analysis.

WARNING: When MCMC model fits fail to converge or yield unphysical parameters resulting in fpp_prob = NaN, other input columns may also be assigned empty values even when other more suitable properties are available. There are 178 KOIs that failed to yield satisfactory model fits and may have empty values in multiple columns as a result.

Questions about the structure and use of this table in the archive format should be submitted through the Exoplanet Archive's Help Desk. Questions about the content descriptions should be sent to the Kepler Science Center.




Database Column Name Table Label Description Uncertainties Column
(positive +)
(negative -)
kepid† KepID Kepler identification  
kepoi_name† KOI Name KOI name  
fpp_koi_period† KOI Transit Period [days] Orbital period of this KOI used in the False Positive probability analysis  
fpp_prad† Planet Radius Value [Earth radii] Planet radius (planet/star radius ratio used [fpp_ror] times stellar radius from Kepler Stellar table) [Earth radii]  
fpp_probv Probability to be Any of the Considered Astrophysical False Positive Scenarios Probability of KOI to be any of the considered astrophysical false positive scenarios, determined by vespa calculation.  
fpp_score†

DR24: Sum of Likelihood for All of the Considered Models

DR25: Shape Score

DR24: Sum of likelihood * prior for all of the considered models (eb, heb, beb, planet); a measure of the reliability of the calculation. Very small numbers (e.g., <1e-10) indicate that none of the models is a good fit, indicating perhaps an instrumental or stellar variability-triggered false alarm. For such KOIs, the fpp value should not be considered reliable.

DR25: In an attempt to make up for the fact that vespa does not consider instrumental false alarms, two artificial (i.e. non-astrophysical) models (called "boxy" and "long") are fit to the data. The individual probabilities for these two artificial models are not listed in the table, but 'fpp_score' = 1 - pr('boxy') - pr('long'). As such, it represents the probability the signal is NOT consistent with one of the artificial models. Note that the definition of fpp_score has changed relative to the DR24 table.

 
fpp_delivname† Name of Delivery The table delivery name from the Kepler Project.  
fpp_spec_occrate† Specific Planet Occurrence Rate Specific planet occurrence rate (integral of Fressin+ (2013) planet occurrence rate over bin from 0.7*rp to 1.3*rp) used to calculate FPP.  
fpp_secthresh† Maximum Allowed Secondary Eclipse Depth [ppm]

DR24:Maximum allowed secondary-eclipse depth [ppm]. This value is taken from the DR-24 robovetter table model-shift secondary tests, calculated as follows:

max(D_sec_dv * (1+3*F_red_dv/sig_sec_dv), D_sec_alt * (1+3*F_red_alt/sig_sec_alt).

For KOIs not in the DR-24 list, this number is taken from the internal weakSecondary_socv9p2vv.csv file provided by the Kepler Science Office. If a KOI is not in that table either, it is estimated to be 10x the pipeline-reported depth error koi_depth_err1.

DR25: Maximum allowed secondary-eclipse depth [ppm].

This value is computed using metrics tabulated in the DR25 robovetter OBS input table, specifically those metrics related to the model-shift secondary tests. The maximum allowed secondary eclipse depth is calculated as follows:

max(mod_depth_sec_dv * (1+3*mod_fred_dv/mod_sig_sec_dv), mod_depth_sec_alt * (1+3*mod_fred_alt/mod_sig_sec_alt).

This value is described in more detail in Section 3 of Morton et al. (2016).

 
fpp_maxrad† Maximum Allowed Sky-Projected Distance for False Positive Scenarios [arcsec] Maximum sky-projected distance allowed for false positive [arcsec]. This is to be taken to be either max(3*koi_dicco_msky_err, 0.5), or a default of 4" if koi_dicco_msky_err is not available.  
fpp_prob_heb† Probability to be a Hierarchical Eclipsing Binary Probability of KOI to be a hierarchical eclipsing binary false positive, determined by vespa calculation.  
fpp_prob_ueb† Probability to be an Unblended Eclipsing Binary Probability of KOI to be an unblended eclipsing binary false positive, determined by vespa calculation.  
fpp_prob_beb† Probability to be a Blended Eclipsing Binary Probability of KOI to be an blended eclipsing binary false positive (chance-aligned, not hierarchical), determined by vespa calculation.  
fpp_prob_heb_dbl† Probability to be Double Period Hierarchical Eclipsing Binary Probability of KOI to be a double period hierarchical eclipsing binary false positive, determined by vespa calculation.  
fpp_prob_ueb_dbl† Probability to be a Double Period Unblended Eclipsing Binary Probability of KOI to be a double period unblended eclipsing binary false positive, determined by vespa calculation.  
fpp_prob_beb_dbl† Probability to be a Double Period Blended Eclipsing Binary Probability of KOI to be a double period blended eclipsing binary false positive (chance-aligned, not hierarchical), determined by vespa calculation.  
fpp_fail_reason Reason for Failure Probabilities are not reported when the calculation fails. The reasons for failure are: UnphysicalPeriod, UnphysicalMCMC, NoMCMC, TrapMCMCNotConverged, NoStellar, and Other.  
fpp_ror† Planet-Star Radius Ratio Planet/star radius ratio used, based on MCMC fits (Jason Rowe)  
fpp_steff† Stellar Effective Temperature [K] Stellar effective temperature [K] based on MultiNest fit to Dartmouth stellar model grids, used in FPP calculations (+) fpp_steffderr1
(-) fpp_stefferr2
fpp_logg Stellar Surface Gravity [log10(cm/s**2)]] Stellar surface gravity [cgs] based on MultiNest fit to Dartmouth stellar model grids, used in FPP calculations (+) fpp_loggderr1
(-) fpp_loggerr2
fpp_smet Stellar Metallicity [dex] Stellar [Fe/H] based on MultiNest fit to Dartmouth stellar model grids, used in FPP calculations [dex] (+) fpp_smetderr1
(-) fpp_smeterr2
fpp_srad† Stellar Radius [Solar radii] Stellar radius [solar] based on MultiNest fit to Dartmouth stellar model grids, used in FPP calculations (+) fpp_sraderr1
(-) fpp_sraderr2
fpp_smass† Stellar Mass [Solar mass] Stellar mass [solar] based on MultiNest fit to Darthmouth stellar model grids, used in FPP calculations (+) fpp_smasserr1
(-) fpp_smasserr2
fpp_sage† Stellar Age [yr] log_10 of stellar age [yr] baed on MultiNest fit to Dartmouth stellar model grids, used in FPP calculations (+) fpp_sageerr1
(-) fpp_sageerr2
fpp_dist† Stellar Distance [pc] Stellar distance [pc] based on MultiNest fit to Dartmouth stellar model grids, used in FPP calculations (+) fpp_disterr1
(-) fpp_disterr2
fpp_av† Av Extinction [mag] A_V extinction [mag], based on MultiNest fit to Dartmouth stellar model grids, used in FPP calculations (+) fpp_averr1
(-) fpp_averr2
fpp_max_av Maximum Allowed Av Extinction [mag] Maximum A_V extinction [mag], based on dust extinction models (+) fpp_maxaverr1
(-) fpp_maxaverr2
fpp_pr_steff_mu Prior Stellar Effective Temperature Mean [K]

DR24: Mean of stellar effective temperature prior use in MultiNest fit, taken from the Q1-Q16 stellar catalog [K]

DR25: Mean of the stellar effective temperature prior used in the MultiNest fit, taken from the DR25 star properties catalog. Priors for the stellar fit were only used in cases where stellar properties have spectroscopic provenances as indicated by the teff_prov flag in the DR25 star properties catalog. All other KOIs (5,370 total) contain empty values.

 
fpp_pr_steff_sig Prior Stellar Effective Temperature Standard Deviation [K] Standard deviation of stellar effective temperature prior use in MultiNest fit, taken from the Q1-Q16 stellar catalog [K]  
fpp_pr_slogg_mu Prior Stellar Surface Gravity Mean [log10cm/s**2)]

DR24: Mean of stellar surface gravity prior use in MultiNest fit, taken from the Q1-Q16 stellar catalog [cgs]

DR25: Mean of the stellar surface gravity prior used in the MultiNest fit, taken from the DR25 star properties catalog. Priors for the stellar fit were only used in cases where stellar properties have spectroscopic provenances as indicated by the teff_prov flag in the DR25 star properties catalog. All other KOIs (5,370 total) contain empty values.

 
fpp_pr_slogg_sig Prior Stellar Surface Gravity Standard Deviation [log10(cm/s**2)]

DR24: Standard deviation of stellar surface gravity prior use in MultiNest fit, taken from the Q1-Q16 stellar catalog [cgs]

DR25: Standard deviation of stellar surface gravity prior used in MultiNest fit, taken from the DR25 star properties catalog. Priors for the stellar fit were only used in cases where stellar properties have spectroscopic provenances as indicated by the teff_prov flag in the DR25 star properties catalog. All other KOIs (5,370 total) contain empty values.

 
fpp_pr_smet_mu Prior Stellar Metallicity Mean [dex] Mean of stellar [Fe/H] prior use in MultiNest fit, taken from the Q1-Q16 stellar catalog [dex]  
fpp_pr_smet_sig Prior Stellar Metallicity Standard Deviation [dex]

DR24:Standard deviation of stellar [Fe/H] prior use in MultiNest fit, taken from the Q1-Q16 stellar catalog [dex]

DR25: Standard deviation of stellar [Fe/H] prior used in MultiNest fit, taken from the DR25 star properties catalog. Priors for the stellar fit were only used in cases where stellar properties have spectroscopic provenances as indicated by the teff_prov flag in the DR25 star properties catalog. All other KOIs (5,370 total) contain empty values.

 
† Default column: these columns display in the interactive table when the table is first loaded, and when Reset Filters is clicked.


Last updated: 20 September 2017