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Kepler Guest Observer Program

Contributed Software - KEPFIELD

Software: PyKE
Version: 1.0.0

Figure 1: Contents of the pixel mask collected around KIC 8256049 during the 2,177th observation of quarter 5. The image intensity scale is linear with the YlOrBr matplotlib color map. Green circles map positions of Kepler Input Catalog (KIC) sources. The larger the circle, the brighter the target. Red circles correspond to the positions of sources listed within deeper source surveys stored at MAST such as the UKIRT J-band survey, Kepler-INT Survey, UBV survey and GALEX survey. The blue solid line navigates the borders of the photometric aperture containing those pixels summed by the Kepler pipeline to produce the archived light curve. The blue dashed line traces the shape of the pixel mask collected from the spacecraft. An extra halo of sky around the pixels collected is included in the plot to provide warning of potential photometric bias from the PSF wings of more distant neighbors. The example above is a planet candidate false positive (KOI-909) - a transit like signal in KIC 8256049 is due to light from the J = 18.9 eclipsing binary to the lower-right of the target falling within the photometric aperture.

kepfield -- Superimpose photometric mask and source positions over a target pixel image

kepfield infile plotfile rownum imscale cmap lcolor verbose logfile status

infile = string
The name of a MAST standard format FITS file containing Kepler Target Pixel data within the first data extension.

plotfile = string
Name of an optional output plot file containing the results of kepfield. An example is provided in Figure 1. Typically this is a PNG format file. If no file is required, plotfile can be 'None' or blank, in which case the plot will be generated but the plot will not be saved to a file. Any existing file with this name will be automatically overwritten.

imscale = String
kepfield can plot images with three choices of image scales. The choice is made using this argument. The Options are: linear | logarithmic | squareroot

cmap = string (optional)
Color intensity scheme for the image display. Options:
Accent | Blues | BrBG | BuGn | BuPu | Dark2 | GnBu | Greens | Greys | OrRd | Oranges | PRGn | Paired | Pastel1 | Pastel2 | PiYG | PuBu | PuBuGn | PuOr | PuRd | Purples | RdBu | RdGy | RdPu | RdYlBu | RdYlGn | Reds | Set1 | Set2 | Set3 | Spectral | YlGn | YlGnBu | YlOrBr | YlOrRd | afmhot | autumn | binary | bone | brg | bwr | cool | copper | flag | gist_earth | gist_gray | gist_heat | gist_ncar | gist_rainbow | gist_yarg | gnuplot | gnuplot2 | gray | hot | hsv | jet | ocean | pink | prism | rainbow | seismic | spectral | spring | summer | terrain | winter | browse.
If cmap=browse kepdiffim will plot the choices of color map.

lcolor = string
The color of the line that defines the boundaries of the pipeline photometric aperture. These can be chosen in html notation, e.g. black is #000000 and white is #ffffff. The html color scheme can be browsed in multiple online charts.

verbose = boolean (optional)
Print informative messages and warnings to the shell and logfile?

logfile = string (optional)
Name of the logfile containing error and warning messages.

status = integer
Exit status of the script. It will be non-zero if the task halted with an error. This parameter is set by the task and should not be modified by the user.

kepfield plots the flux content of each pixel within a target mask, provides positions of known sources within and close to the mask and defines the photometric aperture chosen by the Kepler pipleine to extract the light curve archived at the MAST. This plot provides diagnostics for understanding the fraction of target flux that falls within the pipeline photometric aperture and potential sources of contaminating flux from nearby sources falling within the aperture. The plot can be used to assess whether a new light curve is worth constructing from a customized aperture or PSF fitting. The user chooses a specific observation to plot from an archived Target Pixel File using the rownum field. There are options to choose image scale - e.g. linear, logarithmic etc - and color map. The positions of known sources close to the target are plotted as green circles (KIC sources) and red circles (fainter non-KIC sources tabulated within the target search form). A sky halo is also plot to reveal sources who's PSF wings may be contributing to the flux within the photometric aperture. Within the shell, each source found nearby is tabulated in terms of CCD row, CCD column, Right Ascension, Declination and, when available, the Kepler bandpass magniude and KIC number. Source information is extracted from the MAST and therefore in order to execute kepfield correctly, the user's machine must be connected to the internet.


  • kepfield infile=kplr008256049-2010174085026_lpd-targ.fits infile=tmp.png rownum=2177 imscale=linear colmap=YlOrBr lcolor=#0000ff verbose=y logfile=kepfield.log

Completion upon one target pixel file image using a 2.66 GHz Intel Core 2 i7 Mac running OS 10.6.7, takes a few seconds, depending upon network speed.

The Kepler PyRAF package is made available to the community through the Kepler Science Center at http://keplerscience.arc.nasa.gov/PyKE.shtml. Please send bug reports and suggestions keplergo@mail.arc.nasa.gov.


Initial software release (MS)


Questions concerning Kepler's science opportunities and open programs, public archive or community tools? Contact us via the email address.
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Editor: Martin Still
NASA Official: Jessie Dotson
Last Updated: Jan 11, 2013
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