Kepler Science Operations Center architecture

Abstract

We give an overview of the operational concepts and architecture of the Kepler Science Processing Pipeline. Designed, developed, operated, and maintained by the Kepler Science Operations Center (SOC) at NASA Ames Research Center, the Science Processing Pipeline is a central element of the Kepler Ground Data System. The SOC consists of an office at Ames Research Center, software development and operations departments, and a data center which hosts the computers required to perform data analysis. The SOC's charter is to analyze stellar photometric data from the Kepler spacecraft and report results to the Kepler Science Office for further analysis. We describe how this is accomplished via the Kepler Science Processing Pipeline, including the hardware infrastructure, scientific algorithms, and operational procedures. We present the high-performance, parallel computing software modules of the pipeline that perform transit photometry, pixel-level calibration, systematic error correction, attitude determination, stellar target management, and instrument characterization. We show how data processing environments are divided to support operational processing and test needs. We explain the operational timelines for data processing and the data constructs that flow into the Kepler Science Processing Pipeline.

Pixel-level calibration in the Kepler Science Operations Center pipeline

“…In some calibration steps, such as the black and dark level estimation, CAL interpolates across missing cadences. The only cases for which data may be gapped within CAL include (1) cadences that occur during a momentum dump, (2) cadences that occur when the spacecraft is not in fine point (when the spacecraft attitude is not precisely controlled by the fine guidance sensors 12 ), and (3) masked or virtual columns that have excess flux due to saturated stars that bleed into those columns.…”

“…Each of the 21 modules is composed of four CCD "outputs" that are each read out by a separate analog signal chain. The module integers range from [2-4, 6-20, 22-24], and the output integers range from [1][2][3][4]. Four fine guidance sensors (FGSs) on the corners of the focal plane (modules [1,5,23,25], not shown in Figure 1) collect pointing information rather than science data and are not processed in the Pipeline.…”

Photometer performance assessment in Kepler science data processing

“…Photometer Performance Assessment (PPA) is one of the software components of the science data processing pipeline of the Kepler mission 3,4 . One task of PPA is to analyze the health and performance of the Kepler photometer.…”

The Kepler Science Operations Center pipeline framework extensions

“…It can be configured to include or exclude specific module/outputs. Attributes of the descriptor include the module number (2-4, 6-20, 22-24), the output number (1)(2)(3)(4), and the start and end absolute time index numbers. The generator first creates a descriptor for each time index interval, and then sub-divides each of those descriptors into a descriptor per module/output.…”