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

Christiansen, Jessie L.; Jenkins, Jon M.; Barclay, Thomas; Burke, Christopher J.; Caldwell, Douglas A.; Clarke, Bruce; Li, Jie; Seader, Shawn; Smith, Jeffrey C.; Stumpe, Martin C.; Tenenbaum, Peter; Thompson, Susan E.; Twicken, Joseph D.; Cleve, Jeffrey Van

doi:10.1086/668847

Cited by 253 publications

(196 citation statements)

References 22 publications

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“…A quadratic dependence of photometric precision on the star's boresight is evident for faint stars, and a weak linear dependence is measured for bright stars, with worsening precision at larger distances. See the electronic edition of the PASP for a color version of this figure. boresight was noticed by Christiansen et al (2012), who attributed the effect to the quality of the telescope's focus, which is best between 3-6°from the center of the field. We speculate that the focus quality affects faint stars more than bright stars because they are closer to background-limited photometric precision.…”

Section: Position Dependent Photometric Precisionmentioning

confidence: 99%

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A Technique for Extracting Highly Precise Photometry for the Two-WheeledKeplerMission

Vanderburg

Johnson

2014

Publications of the Astronomical Society of the Pacific

554

631

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ABSTRACT. The original Kepler mission achieved high photometric precision thanks to ultrastable pointing enabled by use of four reaction wheels. The loss of two of these reaction wheels reduced the telescope's ability to point precisely for extended periods of time, and as a result, the photometric precision has suffered. We present a technique for generating photometric light curves from pixel-level data obtained with the two-wheeled extended Kepler mission, K2. Our photometric technique accounts for the nonuniform pixel response function of the Kepler detectors by correlating flux measurements with the spacecraft's pointing and removing the dependence. When we apply our technique to the ensemble of stars observed during the Kepler Two-Wheel Concept Engineering Test, we find improvements over raw K2 photometry by factors of 2-5, with noise properties qualitatively similar to Kepler targets at the same magnitudes. We find evidence that the improvement in photometric precision depends on each target's position in the Kepler field of view, with worst precision near the edges of the field. Overall, this technique restores the median-attainable photometric precision within a factor of two of the original Kepler photometric precision for targets ranging from 10th to 15th magnitude in the Kepler bandpass, peaking with a median precision within 35% to that of Kepler for stars between 12th and 13th magnitude in the Kepler bandpass.

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Section: Position Dependent Photometric Precisionmentioning

confidence: 99%

“…Kepler's scientific impact comes from its ability to monitor a large field of view with highly precise, high-duty cycle photometry for extended periods of time (≃10 parts per million [ppm] per 6 hr for 10th magnitude stars, Christiansen et al [2012]). …”

Section: Introductionmentioning

confidence: 99%

A Technique for Extracting Highly Precise Photometry for the Two-WheeledKeplerMission

Vanderburg

Johnson

2014

Publications of the Astronomical Society of the Pacific

554

631

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“…Assuming loss through tidal evolution, we are then able to compute the maximum moon mass that can survive for 5 Gyr using the expressions of Barnes & O'Brien (2002). This maximum moon mass is then converted into a radius using an appropriate mass-radius relation and finally into a signal-to-noise ratio (S/N) using the Kepler Combined Differential Photometric Precision (CDPP) statistics (Christiansen et al 2012). Target KOIs were selected from the NASA Exoplanet Archive list of KOIs, excluding objects flagged as FPs.…”

Section: Target Selection Automaticmentioning

confidence: 99%

“…Despite the groundbreaking precision achieved by Kepler (Christiansen et al 2012), when one seeks low signal-to-noise events then the effects of time-correlated noise become important. This is particularly salient for exomoons, since the transits do not follow a simple ephemeris which can be used to check for repeatability (Kipping 2011).…”

Section: The Effects Of Correlated Noisementioning

confidence: 99%

THE HUNT FOR EXOMOONS WITHKEPLER(HEK). V. A SURVEY OF 41 PLANETARY CANDIDATES FOR EXOMOONS

Kipping

Schmitt²,

Huang

et al. 2015

ApJ

109

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We present a survey of 41 Kepler Objects of Interest (KOIs) for exomoons using Bayesian photodynamics, more than tripling the number of KOIs surveyed with this technique. We find no compelling evidence for exomoons although 13 KOIs yield spurious detections driven by instrumental artifacts, stellar activity, and/or perturbations from unseen bodies. Regarding the latter, we find seven KOIs exhibiting >5 σ evidence of transit timing variations, including the "mega-Earth" Kepler-10c, likely indicating an additional planet in that system. We exploit the moderately large sample of 57 unique KOIs surveyed to date to infer several useful statistics. For example, although there is a diverse range in sensitivities, we find that we are sensitive to Pluto-Charon mass-ratio systems for ;40% of KOIs studied and Earth-Moon mass-ratios for 1 in 8 cases. In terms of absolute mass, our limits probe down to 1.7 Ganymede masses, with a sensitivity to Earth-mass moons for 1 in 3 cases studied and to the smallest moons capable of sustaining an Earth-like atmosphere (0.3 M ⊕ ) for 1 in 4. Despite the lack of positive detections to date, we caution against drawing conclusions yet, since our most interesting objects remain under analysis. Finally, we point out that had we searched for the photometric transit signals of exomoons alone, rather than using photodynamics, we estimate that 1 in 4 KOIs would have erroneously been concluded to harbor exomoons due to residual time correlated noise in the Kepler data, posing a serious problem for alternative methods.

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“…1c for Kepler-17. We used the CDPP (Combined Differential Photometric Precision, see Christiansen et al (2012) as an estimation of the noise in the Kepler data. Each quarter of the light curve has an associated CDPP value.…”

Section: Spot Modelmentioning

confidence: 99%

Using planetary transits to estimate magnetic cycles lengths in Kepler stars

Estrela

Válio

2016

Proc. IAU

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Abstract. Observations of various solar-type stars along decades revealed that they can have magnetic cycles, just like our Sun. An investigation of the relation between their cycle length and rotation period can shed light on the dynamo mechanisms operating in these stars. Previous works on this relation suggested that the stars could be separated into active and inactive branches, with the Sun falling between them. In this work, we determined short magnetic activity cycles for 6 active solar-type stars observed by the Kepler telescope. The method adopted here estimates the activity from the excess in the residuals of the transitlight curves. This excess is obtained by subtracting a spotless model transit from the light curve, and then integrating over all the residuals during the transit. The presence of long term periodicity is estimated from the analysis of a Lomb-Scargle periodogram of the complete time series. Finally, we investigate the rotation-cycle period relation for the stars analysed here and find that some active stars do not follow the behaviour proposed earlier, falling in the inactive branch. In addition, we also notice a considerable spread from other stars in the literature in the active/inactive branches.

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

Cited by 253 publications

References 22 publications

A Technique for Extracting Highly Precise Photometry for the Two-WheeledKeplerMission

A Technique for Extracting Highly Precise Photometry for the Two-WheeledKeplerMission

THE HUNT FOR EXOMOONS WITHKEPLER(HEK). V. A SURVEY OF 41 PLANETARY CANDIDATES FOR EXOMOONS

Using planetary transits to estimate magnetic cycles lengths in Kepler stars

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