DATA PROCESSING PIPELINE

OVERVIEW

Data collected by the photometer are recorded on orbit, downlinked, archived, and end up at the Space Science Division of NASA's Ames Research Center. All science data is processed and calibrated through the Kepler Science Pipeline. The pipeline converts raw data numbers, pixel locations, and ancillary engineering data into calibrated counts and astrometric coordinates. After summing the counts within defined apertures, estimating and subtracting background light, and adjusting for cosmic rays, calibrated light curves are created for each selected source. Further processing corrects these light curves for a variety of instrumental artifacts and conditions the data for the next step, a numerical search for candidate planetary transit events. These candidate transits are then validated in the final processing stage.

Processed data is written to FITS-formatted files and exported to the MAST archive at the Space Telescope Science Institute. The archived data includes the raw and calibrated pixel values for all sources, background pixels, calibrated and corrected light curves, and related ancillary engineering data. Results of the transit search segment of the pipeline are not archived; these data inform the science team of planet candidates for followup investigation. The specific data products and content archived at MAST will change during the course of the mission. Users should examine the Archive Manual, the Data Release Notes, and the Data Products page to track these changes.
All users not resident at NASA-Ames obtain their data via MAST.
 

Users are strongly encouraged to review the following papers, a subset of the Kepler documentation, prior to working with the data. These papers describe the science operations, processing and characteristics of the light curves. As our understanding of the instrument progresses, additional discussion of systematic error mitigation, data quality issues, and calibration will be provided. In addition to these peer-reviewed papers, the user is also directed to the Kepler Instrument Handbook, the Data Release Notes, the Data Charactistics Handbook, all available at MAST.

OPERATIONS, PROCESSING, and DATA PROPERTIES

1. KEPLER MISSION DESIGN, REALIZED PHOTOMETRIC PERFORMANCE, AND EARLY SCIENCE
   Koch, David G., etal, 2010, ApJ, 713, L79

2. KEPLER SCIENCE OPERATIONS
   Haas, Michael R., etal, 2010, ApJ, 713, L115

3. INSTRUMENT PERFORMANCE IN KEPLER'S FIRST MONTHS
   Caldwell, Douglas A., etal, 2010, ApJ, 713, L92

4. OVERVIEW OF THE KEPLER SCIENCE PROCESSING PIPELINE
   Jenkins, Jon M., etal, 2010, ApJ, 713, L87

5. THE KEPLER PIXEL RESPONSE FUNCTION
   Bryson, Stephen T., etal, 2010, ApJ, 713, L97

6. INITIAL CHARACTERISTICS OF KEPLER SHORT CADENCE DATA
   Gilliland, Ronald L., etal, 2010, ApJ, 713, 160

7. INITIAL CHARACTERISTICS OF KEPLER LONG CADENCE DATA FOR DETECTING PLANET TRANSITS
   Jenkins, J. etal, 2010 ApJ 713, 120

8. PRELIMINARY ASTROMETRIC RESULTS FROM KEPLER
   Monet, David G., etal, 2010, ApJ, submitted

PIPELINE COMPONENTS

Each processing step is executed via a software module, developed and implemented by the Science Operations Center (the "SOC") at NASA Ames. Each module is composed of a number of procedures coded in Matlab. A global schematic of the pipeline flow is presented below. The principal elements of the pipeline are entitled (followed by their common use abbreviations):

• CALIBRATION   (CAL)
• PHOTOMETRIC ANALYSIS   (PA)
• PRE-SEARCH DATA CONDITIONING   (PDC)
• TRANSITING PLANET SEARCH   (TPS)
• DATA VALIDATION   (DV)

Users should note that in the current pipeline (SOC 6) the term raw flux light curves are actually derived from calibrated pixels, a somewhat confusing nomenclature. "Raw" light curves was adopted to differentiate between light curves summed directly from the assigned apertures - the output of PA, and light curves corrected for instrumental artifacts and other known systematics errors - the output from PDC.

Schematic of the Kepler Processing Pipeline. The primary software modules are indicated on the left.