Once the axes have been selected and any selection criteria specified, pushing the
Image button initiates dialogue panels that includes an Image
section like that shown in figure 34 which gives the
opportunity to review the choices made. The
BETA_CORR/PI images, commonly
known as banana plots, are improved by overruling the default y-range by checking
withyranges box and setting
Figure 35 shows plots of the merged RGS1 events. These plots
are orthogonal projections of the all-important
3-D RGS data space of the merged list of all the events detected in the observation,
thus showing all the features, both good and not so good, of RGS data.
The edges are clear of the 9 CCDs, numbered 1-9 from right to left. In both plots,
wavelength and dispersion angle increase from left to right.
From quite early in the
mission, each RGS has been missing data from one CCD because of electronics
failures, RGS1 CCD7 and RGS2 CCD4, that happily do not cover the same wavelengths.
The pointing coordinates were evidently chosen well enough to put this bright source
central in the aperture. The source was bright enough to be seen up to
4th or even a weak 5th order in the characteristic hyperbolic-shaped areas
occupied by photons that have passed through
the gratings. There are plenty of hot pixels and columns
and the so-called fixed pattern noise shows as the herring-bone pattern in
CCDs 8 and 9. Calibration sources of
F K at
PIeV span CCDs 2&3 and 7&8 ; and Al K
PIeV span CCDs 3&4 and 8&9.
The locations of the selection regions may be checked using the task rgsimplot
which plots them over
BETA-PI images that are,
in this case, most usefully generated from the screened
events files. Figure 36 shows such an example.