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Displaying KEPLER Light Curves

This document describes how to select, display, and optionally customize the dsiplay of Kepler light curves.

Selecting Targets
Up to 15 observations can be co-plotted using the "mark" buttons on the Kepler "Data Search" results page. To mark all entries for plotting, click one of the buttons labelled 'Mark All','Mark public', or 'Mark Proprietary'. (Unmarking all entries can be done the same way using the appropriate button.) For missions with proprietary data, the mark button element will have a yellow background and a '@' symbol to indicate data sets not yet public. Currently only public light curves can be displayed, but this may change in the future. Once the data sets are selected, click the "Plot marked spectra" button. Remember to unmark previous selections before plotting a new target light curve.

The plot will be displayed as a .png file with axes automatically scaled to the min and max values of the plotted light curves. Each light curve is automatically assigned a color, up to a maximum of 15. It is recommended that only light curves from the same target be co-plotted due to the differences in flux values. By default, both the raw (uncorrected) and corrected fluxes will be displayed iin histogram format in the same color for each data set, with a dashed line (which is sometimes hard to see) representing the uncorrected light curve. Either corrected or uncorrected fluxes can also be plotted separately, although the "autio-scaling" option should be selected each time in order to set the initial plot axes. When plotted separately, all light curves are displayed as solid lines.

The x-axis displays Modified Julian Date in days. For data obtained after Data Release 2, the time is calculated as time[i] - (timecor[i]/(60.0*60.0*24.0)) - 0.5; where time[i] = barytime from the ith value in column 1 from the FITS binary table file and timecorr[i] = the ith value for the time correction from column 2. For data from Data Release 2 and earlier, the plotted time is calculated as time[i] + (lc_start/(60.0*60.0*24.0)) where time[i] = the ith value from column 1 of the binary table and lc_start = the date extracted from the LC_START FITS keyword.

The light curves are labelled by their dataset names, with a short summary of each dataset below the plot indicating

  • data set name,
  • the data release of the plotted data,
  • type of data plotted (corrected,uncorrected, or both),
  • number of points removed (i.e., those having a value of -inf),
  • and the time range.
After inspecting the plot, you may wish to change the selection of datasets which are displayed. Use your browser "Back" button to do this.

Plot Options

Select Data
One may display the corrected flux (currently column 10 in the Kepler binary table FITS file), the uncorrected (raw) flux (from binary table column 8), or both (the default). Light curves prior to Data Release 3 will only display unccrected fluxes (originally binary table column 7).

Plot range
Adjust the minimum and maximum time period (in days) and minimum and maximum fluxes (currently in e-/cadence) to select the region of interest and/or to exclude noisy data. Click the "autoscale" button to automatically set the plot range to the min and max values.

Plot dimensions
Adjust the X size and Y size in pixels to create the size of plot desired. The maximum dimensions are 850 by 640 pixels.

Scale Factors
The scale factors allow the light curve(s) from one data set to be scaled relative to the other plotted light curves.

Redraw plot
Use this button to replot the spectra when you have changed the plot range or plot dimensions.