The Derivation, Properties, and Value of Kepler’s Combined Differential Photometric Precision

By J. Christiansen, Jon M. Jenkins, T. Barclay, C. Burke, Douglas A. Caldwell, B. Clarke, Jie Li, S. Seader, Jeffrey C. Smith, Martin C. Stumpe and 4 more. 2012

207 citations recorded by the source corpus.

The Kepler Mission is searching for Earth-size planets orbiting solar-like stars by simultaneously observing >160,000 stars to detect sequences of transit events in the photometric light curves. The Combined Differential Photometric Precision (CDPP) is the metric that defines the ease with which these weak terrestrial transit signatures can be detected. An understanding of CDPP is invaluable for evaluating the completeness of the Kepler survey and inferring the underlying planet population. This paper describes how the Kepler CDPP is calculated, and introduces tables of rms CDPP on a per-target basis for 3-, 6-, and 12-hr transit durations, which are now available for all Kepler observations. Quarter 3 is the first typical set of observations at the nominal length and completeness for a quarter, from 2009 September 18 to 2009 December 16, and we examine the properties of the rms CDPP distribution for this data set. Finally, we describe how to employ CDPP to calculate target completeness, an important use case.

Subfields: Astronomy and Astrophysics, Atmospheric Science

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. D. Charbonneau
2. Timothy Morton
3. J. Johnson
4. J. Winn
5. Andrew W. Howard
6. G. Marcy
7. Jon Fortney
8. E. Gaidos

In Atmospheric Science

1. Mercedes López-Morales
2. D. Charbonneau
3. A. Mann
4. R. Barnes
5. J. Johnson
6. E. Hilton
7. G. Esquerdo
8. K. Heng

Citations in the corpus

• A SYSTEMATIC SEARCH FOR TRANSITING PLANETS IN THE K2 DATA (2015, methodology): “Following Vanderburg & Johnson (2014), we choose the aperture size with the minimum CDPP (Christiansen et al. 2012) with a 6 hour window.3 All previous methods for analyzing K2 data involve some sort of “correction” or “de- trending” step based on measurements of the pointing of the spacecraft (Vand”
• THE RADIUS DISTRIBUTION OF PLANETS AROUND COOL STARS (2013, methodology): “…exact observing window function, this prescription for cal- culating SNR is exactly the use case of the CDPP values as recommended by the Kepler team (Christiansen et al. 2012), especially since most of the targets in this survey are faint and thus white-noise dominated on the timescale of…”
• Planet Hunters IX. KIC 8462852-where's the flux? (2015, methodology): “Kepler data files provide both the ‘uncorrected’ Simple Aperture Photometry (SAP) and the ‘corrected’ Pre-search Data Conditioning (PDCSAP) fluxes (for details, see Christiansen et al. 2012).”
• CONTAMINATION IN THE KEPLER FIELD. IDENTIFICATION OF 685 KOIs AS FALSE POSITIVES VIA EPHEMERIS MATCHING BASED ON Q1–Q12 DATA (2014, background): “A photometric precision of ∼40 ppm is attained on a 6-hour timescale for a 12th magnitude star (Christiansen et al. 2012).”
• FUNDAMENTAL PROPERTIES OF KEPLER PLANET-CANDIDATE HOST STARS USING ASTEROSEISMOLOGY (2013, unknown): “(6) Here, R is the host-star radius, S/N is the required signal-tonoise ratio, σCDPP is the 6 hr combined differential photometric precision (Christiansen et al. 2012), ntr is the number of transits (A color version of this figure is available in the online journal.) observed and tdur is the…”
• THE OCCURRENCE RATE OF SMALL PLANETS AROUND SMALL STARS (2013, methodology): “We determine σCDPP by fitting a curve to the observed Combined Differential Photometric Precision (CDPP; Christiansen et al. 2012) measured for each star over 3- hr, 6-hr, and 12-hr time periods and then interpolating to find the expected CDPP for the predicted transit duration.”
• Trumpeting M dwarfs with CONCH-SHELL: a catalogue of nearby cool host-stars for habitable exoplanets and life (2014, methodology): “…days, for all quar- ters where a star was observed, and estimated ∑16 i=1 σ −2 i at a given t by interpolating or extrapolating from values at 3, 6, and 12 hr estimated with the corresponding values of the Combined Differential Photometric Precision (CDPP) for each star (Christiansen et al. 2012).”
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission (2014, background): “Kepler’s scientific impact comes from its ability to monitor a large field of view with highly precise, highduty cycle photometry for extended periods of time (≃ 10 parts per million (ppm) per 6–hours for 10th magnitude stars, Christiansen et al. 2012).”
• EVEREST: PIXEL LEVEL DECORRELATION OF K2 LIGHT CURVES (2016, methodology): “The dashed red and solid blue lines indicate the median CDPP in 0.5 magnitude-wide bins in the raw and de-trended light curves, respectively.”
• The California-Kepler Survey. V. Peas in a Pod: Planets in a Kepler Multi-planet System Are Similar in Size and Regularly Spaced (2017, background): “The expected SNR of a planet with size Rp and orbital period P orbiting a star with bulk density ρ?, radius R?, and 6-hour Combined Differential Photometric Precision (CDPP6h, a measure of the stellar photometric noise over 6 hours, Christiansen et al. 2012) is: SNR = (Rp/R?)”
• Precise time series photometry for the Kepler-2.0 mission (2014, unknown): “However, we cannot reproduce the actual CDPP values without access to the transit search component of the Kepler pipeline, since the CDPP is essentially the depth of a transit of a given duration that would give a signal-to-noise ratio of 1 (Christiansen et al. 2012).”
• PLANETARY CANDIDATES OBSERVED BY KEPLER IV: PLANET SAMPLE FROM Q1–Q8 (22 MONTHS) (2013, background): “TPS empirically determines the noise in the flux time series (combined differential photometric precision, CDPP, Christiansen et al. 2012) of each target to search for potential planet candidates (threshold crossing events, TCEs) (Jenkins 2002; Tenenbaum et al. 2012).”
• Identifying Exoplanets with Deep Learning: A Five-planet Resonant Chain around Kepler-80 and an Eighth Planet around Kepler-90 (2017, background): “…NASA’s Kepler Space Telescope observed about 200,000 stars photometrically with unprecedented precision (Koch et al. 2010; Jenkins et al. 2010a; Christiansen et al. 2012), discovered thousands of transiting exoplanets (and thousands more planet candidates, Borucki et al. 2011a,b; Batalha et…”
• THE MASS OF Kepler-93b AND THE COMPOSITION OF TERRESTRIAL PLANETS (2014, background): “The host star Kepler-93 (KIC 3544595, KOI 69) is one of the brightest stars observed by Kepler (V = 10.2, Kp = 9.93), enabling very high precision photometry of 17 ppm on six-hour timescales (Christiansen et al. 2012).”
• THE OCCURRENCE OF POTENTIALLY HABITABLE PLANETS ORBITING M DWARFS ESTIMATED FROM THE FULL KEPLER DATASET AND AN EMPIRICAL MEASUREMENT OF THE DETECTION SENSITIVITY (2015, background): “We refer instead to Christiansen et al. (2012) for a discussion of pixel-level effects.”