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

TL;DR

This paper explains how Kepler's Combined Differential Photometric Precision (CDPP) is calculated, its properties, and how it can be used to evaluate survey completeness and detectability of Earth-like planets.

Contribution

It introduces a detailed method for calculating and tabulating Kepler's CDPP, providing a valuable resource for assessing survey completeness and planet detection capabilities.

Findings

Provided rms CDPP tables for all Kepler targets

Analyzed the distribution of rms CDPP in Quarter 3 data

Demonstrated how to use CDPP to estimate target completeness

Abstract

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-hour 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.