Getting Started

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 become available.

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. Since Dec 1, 2010, the tpf files are 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 electrons read-out in the detector per second.) 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.

Data Availability All Kepler data is now public and available online. The data however is expected to be reprocessed, so check for updates.

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 Handbook, 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 "NExScI", services for objects that are part of various exoplanetary surveys.

Registration in the STSCI "DADS" system: Users interested in having an archive account must first register in the STScI archive system. Starting in April 2015, STScI switched to a Single Sign On (SSO) system where one set of credentials is used for access to various systems, including the archive. Since all Kepler data is now public though, it is no longer necessary to have an account. To browse and/or download data for Kepler observed objects, use the Kepler Data Search and Retrieval form.