XMM-Newton Science Analysis System
ekstest (ekstest-2.2.5) [xmmsas_20070708_1801-7.1.0]
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Description
ekstest
reads the FITS file containing the EPIC source and
background time series' produced by lccorr
or elcbuild
and its associated Good Timing Interval (GTI) file produced by
tabgtigen, if required. It eliminates all bins that contain
null or negative values as well as those that are not in the GTIs, if
the GTI file is provided. It can perform any or all of the following
variability tests on the light curve to determine whether the source
is variable, however if insufficient good bins remain, no variability
tests are carried out.
- a Kolmogorov-Smirnov test carried out either on: the cumulative
probability functions of the observed count distribution and the
observed background distribution; or the cumulative probability
function of the observed net count distribution and the cumulative
time distribution. It then writes the Kolmogorov-Smirnov statistic,
the probability that the source is not variable and the number of good
bins used to determine these values into the header of the input file
or into the header of a new file and/or to the screen. It must be
noted that only the Kolmogorov-Smirnov test with the cumulative
probability function of the observed net count distribution and the
cumulative time distribution can be carried out at the same time as
the other tests.
- a chi-squared probability of constancy test on the net
light curve. It then writes the chi-squared statistic, the
probability that the source is not variable and the number of good
bins used to determine these values into the header of the input file
or into the header of a new file and/or to the screen.
- a flare test on the net lightcurve. This searches for
the highest peak in the lightcurve, which is over a threshold value
provided by the user (given in sigma above the median value of the
lightcurve), with an integer number of consecutive bins over the same
threshold, also given by the user. The average sigma of the flare,
above the median value of the lightcurve along with the number of good
bins in the lightcurve are written either into the header of the input
file or into the header of a new file and/or to the screen.
- a variation test between the beginning and the end of the
lightcurve. The user provides the percentage of the lightcurve to be
used at each end and the difference in sigma between the mean values
of the two ends along with the number of good bins in the lightcurve
are written either into the header of the input file or into the
header of a new file and/or to the screen.
The input FITS files must contain net count rates, background count
rates and the associated errors. The time series must follow a regular
binning scheme (i.e. equispaced time bins) [1]. The
bin width is given by the keyword TIMEDEL.
Subsections
XMM-Newton SOC/SSC -- 2007-07-08