Introduction: MAST provides the interface to the archival data for the Kepler mission. The Kepler data are comprised primarily of short (1 minute) and and long (30 minute) cadence light curves and tables known as target pixel files. These tables list the values for the pixels covering the target image. Ancillary products pertaining to the detector focal plane characterization will also be included. Several details of the Kepler mission make it unique from other MAST-archived missions. These include that the data are time sequences, the satellite field of view is fixed on the sky, the satellite is in an Earth-trailing orbit, the mission's core objective has been defined by the Principal Investigator and his Science Team, and the data are processed serially in three locations. These circumstances together determine which, when, and how data can be released to the public and Guest Observers (GOs) of the program.
The data flow: The progress of the data stream, from satellite to archive is as follows: telemetry is read down from the satellite and packaged first as raw data by the Mission Operations Center (MOC) in Boulder, Colorado. The MOC transmits the data to the Data Management Center (DMC) at STScI where they are sorted by long or short cadence and converted to FITS files. The DMC sends these "cadence files" to the Science Operations Center (SOC) at the Ames Research Center, which calibrates the cadence data and constructs light curves and target pixel files (tpf) for individual targets. The calibrated cadence data and the light curves are sent to the DMC for archiving. On or about Dec 1, 2010, the tpf files will be sent to the DMC for archiving. All data are housed in the DADS archive at STScI. Searches and retrievals of Kepler data are conducted through the MAST Data Search and Retrieval form. Note carefully that MAST itself does not construct the data files, but any comments or questions about them from users will be passed on to the group that created them.
Available types of light curves: As noted in the Kepler Data Characteristics Handbook, light curves are available using a "simple aperture photometry" technique. These particular light curves are called "uncorrrected light curves." (Note that these light curves have units of of electrons read-out in the detector over the integration time, "electrons per cadence.) These light curves are not yet corrected for most known instrumental effects. A second light curve, intended to correct for many but not all such effects is called the "PDC" (Pre-Search Data Conditioning) light curve. Light curve files in fits format contain both light curves, and the MAST Light Curve Coplotter by default plots both sets of data for comparison. Users should take note of the units for the data in both the light curves and the target pixel data files. These units are discussed in MAST's Frequently Asked Questions (FAQ) page.
Availability of Public Data: As the mission proceeds, the Project will periodically drop stars as exoplanetary search candidates. As it does so, MAST will expand access to lists of targets and/or data released as notifications in the Dropped Target and Published Target tabs under the Search and Retrieval item on the left banner of this page and in the Public Light Curves link in the Quick Links section of the home page. These lists provide links for the target to the Target Search and Data Search and Retrieval pages. In addition, data for all targets observed after Q13 will become nonproprietary; for GO data this corresponds to Cycle 3. This statement also extends to Key Project and KASC data.
GO Program data rights (Q2-Q13 only): according to NASA policy Guest Observer program data become public at MAST one year after its initial availability to the Principal Investigator or 6 months after the last data for the GO program are archived, whichever is later. As noted above Cycle 3 will be the last year for which proprietary data are extended to GO data; data obtained for Q14 (beginning of Cycle 4) will be released immediately to the public upon ingest at MAST. availability to the Principal Investigator.
Key Project data (Q0-Q13 only) For Kepler Key Project data, the proprietary period was a sliding scale that increases during through Q13. See the Kepler Archive Manual for details of planned releases. Any information on these points that MAST may unintentionally give in conflict with information on the Kepler Project pages should be ignored.
What to read first: We recommend that users get started by reading the Project's Scientific Goals page, the MAST FAQ page, and the technical documentation made available on the left panel of this page. Documentation includes the Kepler Archive Manual, the Kepler Instrument Manual, and the Kepler Data Characteristics Handbook. Users should also consult the Related Sites links, which point to exoplanet research done by other, ground-based, groups. MAST's links include those dedicated to ongoing ground-based observations of stars in the Kepler field of view and, in the case of "NSTeD," services for objects that are part of various exoplanetary surveys.
Initial registration in the STSCI "DADS" system:
Users having rights to proprietary data, including both Team
members and GOs, must first
register in the STScI archive
system. (If you have done this once to retrieve HST or FUSE data, you
do not need to do so again.) To browse and/or download data for
Kepler observed objects, use the Kepler Data Search
and Retrieval form.