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K2 Online Ancillary Files
As was done for Kepler, several types of online ancillary data files
are made available to users. The currently available ones
are described below with links to the corresponding
subdirectories of the K2 directory.
Note that the Long and Short Cadence Collateral (KLL & KLS) files,
Artifact Removal Pixel (KAP) files, and
Background Pixel files (KBG) are stored elsewhere but can be retrieved
using the FFI & Ancillary Data search form.
These file types are documented in the
Kepler Archive Manual
and the differences for K2 products are noted in the K2 Data
Full Frame Image (FFI)
Full frame images of the K2 fields are typically taken twice during
each campaign to confirm the field of view, assess photometer health,
and facilitate calibration.
The FFI files contain both raw and calibrated images as well as
They can be downloaded using the browser at the above link,
anonymous ftp at /pub/k2/ffi, or via the
FFI & Ancillary Data search form.
To display individual channels from any of the FFI images,
and overlay various catalogs,
see the FFI_Display page.
Fine Guidance Sensor Data (FGS)
The FGS data collected throughout the K2 mission are being made available
to the user community
for scientific analysis as flux and centroid time series, along with a limited
number of FGS full frame images which may be useful for constructing a World
Coordinate System (WCS) or otherwise putting the time series data in context.
Starting with Data Release 5, the QUALITY flags included in the light curve
and target pixel FITS files
indicate cadences at which thrusters fired, or may have fired.
Since some campaigns are yet to be reprocessed and others have no light
curve files (e.g., C0, C2, C9a, C9b,C10a) these flags are provided in csv format
with one line per cadence for each cadence type.
Each line utilizes a comma-separated format and reports:
cadence number, definite thruster firing flag, and possible thruster firing flag.
Note these files may contain cadence gaps for periods of time when
standard cadence data was not being collected; typically these correspond
to data download periods or the collection of FFIs.
(See Table 2-3
in the Kepler Archive manual for the definitions of these new bit flags).
Raw Cadence Data
Raw cadence data are generally released immediately after download from the Kepler
spacecraft to facilitate time-critical investigations which would be unduly delayed
by waiting for the pipeline-processed data that contain both calibrated and
uncalibrated pixels in the standard TPF format.
These raw cadence data consist of multiple components, including target pixels,
collateral pixels, and
pixel mapping reference files.
For more information on format and usage, see the document
KADN-26315.pdf, and consider
using Kadenza to convert
these raw data to a more user-friendly file format.
We currently have raw cadence data for campaigns 0 through 16 online.
Two-wheel Concept Engineering Test Data
The data from a 9-day engineering test conducted before Campaign 0 have been
made available as uncalibrated TPFs. These files can be downloaded individually
or as .tgz files (there are 17 targets in the 4 GB short cadence compressed file and
2,079 targets in the 16 GB long cadence compressed file).
To download from the browser use the link above, or
ftp to archive.stsci.edu and cd to /pub/k2/eng. The individual
files can be found in subdirectories labelled "short_cadence" and "long_cadence".
The .csv files provide a brief description of why these targets were observed and
map their engineering IDs to their locations and estimated Kepler magnitudes.
Download Scripts These WGET scripts allow light curve or target pixel file data
to be downloaded for a particular program ID. These scripts
should be downloaded to the users' computer
and run from its command line. They require WGET to be installed on the users'
Previews Previews are various size png plot files showing K2 light curves.