Archive for September, 2011

WWZ contour plots

September 15, 2011

In my last post about WWZ I said this:

What VStar does not currently do is create a 2D plot that represents the WWZ statistic as different colours. It’s an open question as to whether this is necessary, but such plots do have a striking appearance and some may prefer them over 3D plots.

I’ve implemented contour plots for WWZ in VStar now. Here is the plot for the T UMi example in that last post.

T UMi WWZ contour plot

T UMi WWZ contour plot

I may tweak the appearance of these plots yet, but this is essentially what they will look like in the forthcoming release.

This is similar to the example plot in Grant’s book on page 235 (Fig 11.14) except that period is on the Y axis rather than frequency. It’s interesting to compare this against where the peaks occur the 3D plot.

I have also added the ability to:

  1. Request WWZ and DC DFT in terms of period range rather than frequency range;
  2. specify the number of time divisions across the dataset range for WWZ. The improvement in time resolution is most noticeable in the contour plot. In the plot above, I used a value of 80 instead of the default of 50.

An internal VStar team testing release is getting close, hopefully by the end of this week.