J/ApJS/207/35 Kepler pipeline signal-to-noise studies (Christiansen+, 2013)
Measuring transit signal recovery in the Kepler pipeline.
I. Individual events.
Christiansen J.L., Clarke B.D., Burke C.J., Jenkins J.M., Barclay T.S.,
Ford E.B., Haas M.R., Sabale A., Seader S., Smith J.C., Tenenbaum P.,
Twicken J.D., Uddin A.K., Thompson S.E.
<Astrophys. J. Suppl. Ser., 207, 35 (2013)>
=2013ApJS..207...35C 2013ApJS..207...35C
ADC_Keywords: Planets
Keywords: methods: data analysis - planets and satellites: detection
Abstract:
The Kepler mission was designed to measure the frequency of Earth-size
planets in the habitable zone of Sun-like stars. A crucial component
for recovering the underlying planet population from a sample of
detected planets is understanding the completeness of that sample -the
fraction of the planets that could have been discovered in a given
data set that actually were detected. Here, we outline the information
required to determine the sample completeness, and describe an
experiment to address a specific aspect of that question, i.e., the
issue of transit signal recovery. We investigate the extent to which
the Kepler pipeline preserves individual transit signals by injecting
simulated transits into the pixel-level data, processing the modified
pixels through the pipeline, and comparing the measured transit
signal-to-noise ratio (S/N) to that expected without perturbation by
the pipeline. We inject simulated transit signals across the full
focal plane for a set of observations for a duration of 89 days. On
average, we find that the S/N of the injected signal is recovered at
MS=0.9973(±0.0012)xBS-0.0151(±0.0049), where MS is the measured
S/N and BS is the baseline, or expected, S/N. The 1σ width of
the distribution around this correlation is ±2.64%. This indicates
an extremely high fidelity in reproducing the expected detection
statistics for single transit events, and provides teams performing
their own periodic transit searches the confidence that there is no
systematic reduction in transit signal strength introduced by the
pipeline. We discuss the pipeline processes that cause the measured
S/N to deviate significantly from the baseline S/N for a small
fraction of targets; these are primarily the handling of data adjacent
to spacecraft re-pointings and the removal of harmonics prior to the
measurement of the S/N. Finally, we outline the further work required
to characterize the completeness of the Kepler pipeline.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 47 80 S/N recovery for each channel
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/ApJS/199/24 : The first three quarters of Kepler mission (Tenenbaum+, 2012)
http://keplergo.arc.nasa.gov/ : Kepler home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ch [1/84] Channel number
4- 7 I4 --- Ntar [622/2316] Final number of targets used in analysis
9- 15 F7.4 --- a [-0.03/0.002] The a coefficient of the fit (1)
17- 18 I2 10-4 e_a [6/27] The 1σ uncertainty in a
20- 25 F6.4 --- b [0.99/1.01] The b coefficient of the fit (1)
27- 28 I2 10-4 e_b [3/4] The 1σ uncertainty in b
30- 35 F6.4 --- HWHM-G [0.02/0.04] Gaussian Half-Width at Half-Maximum (2)
37- 42 F6.4 --- HWHM-L [0.02/0.05] Lorentzian Half-Width at Half-Maximum
of |(MS-BS)/BS| distribution (1)
44- 45 I2 --- Nsup [0/25] Targets showing significant suppression (2)
47 I1 --- Naug [0/2] Targets showing significant augmentation (2)
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Note (1): where MS = a * BS + b; MS is the measured S/N of the transit
signal processed through the pipeline and BS is the baseline S/N,
both in units of σ.
Note (2): Of their detection statistics, as defined in Sections 4.1 and 5.2.
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History:
From electronic version of the journal
References:
Christiansen et al. Paper II. 2015ApJ...810...95C 2015ApJ...810...95C, Cat. J/ApJ/810/95
Christiansen et al. Paper III. 2016ApJ...828...99C 2016ApJ...828...99C
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 05-Sep-2013