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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.
Display 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.