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TARA

At Penn State inspection of the XRCF data and some analyses were performed using the IDL program Event Browser[*] This program offers a graphical user interface for performing standard visualization and analysis tasks on FITS event lists. The set of events that is of interest may be constrained spatially, spectrally, morphologically (by grade), and temporally. Standard visualizations, such as spectra (in DN or eV), light curves and images, are provided. Basic analysis capabilities, such as fitting a spectral peak to a gaussian model, are provided.

Figure 7.3 shows a light curve plot in Event Browser. The user has control over the histogram binning, error bar display, axis styles (linear or log), axis ranges, titles, symbol & line styles, and color. The box depicts a region-of-interest (ROI) defined by the user. Simple statistics on the X/Y points inside the ROI may be computed. For example this technique could be used to determine the average level and standard deviation of a light curve or to count how many exposures in an interval contained more than zero events.

Figure 7.4 shows a spectrum plot. The vertical lines depict a region-of-interest (ROI) defined by the user and a gaussian model of the data in the ROI has been overplotted.

Figure 7.5 shows a grey-scale image that depicts the spatial distribution of an event list from a defocussed effective area test. The user may plot angled cuts through the image, compute the centroid, and plot radial profiles about the centroid.

Figure 7.6 shows the same dataset with an annular spatial filter applied to select events from one of the four mirror shells.

Figure 7.7 shows a region-of-iterest (ROI) defined on a plot of event energy verses exposure number for a DCM scanning test. The user has configured the ROI so that it acts as a filter that selects only events from one DCM energy dwell.

Other filtering tools allow grade selection, selection by CCD amplifier, etc. One of the strengths of Event Browser is that redefinitions of the filters, changes to the input dataset itself, or changes to various parameters of the reduction (such as the split threshold) produce automatic updates to all the displays (such as spectrum plots). For example it is easy to plot a spectrum with one set of grades, then change the grade filter and overplot the new spectrum for comparison.

Filtered event lists may be saved as FITS event lists or as XSPEC spectral files. Since the user has direct control over plot scaling, titles, colors, and styles, production of presentation-quality plots is straight-forward.


  
Figure 7.3: Event Browser Light Curve
\begin{figure}
\centerline{
\psfig {file=tara/light_curve.ps,height=7.0in}
}\end{figure}


  
Figure 7.4: Event Browser Spectrum
\begin{figure}
\centerline{
\psfig {file=tara/spectrum.ps,height=7.0in}
}\end{figure}


  
Figure 7.5: Event Browser Image
\begin{figure}
\centerline{
\psfig {file=tara/pv_tv.ps,height=7.0in}
}\end{figure}


  
Figure 7.6: Event Browser Spatial Filter
\begin{figure}
\centerline{
\psfig {file=tara/spatial_filter.ps,height=7.0in}
}\end{figure}


  
Figure 7.7: Event Browser Property/Property Filter
\begin{figure}
\centerline{
\psfig {file=tara/2prop_filter.ps,height=7.0in}
}\end{figure}



Footnotes

...Browser
See http://www.astro.psu.edu/xray/docs/ .


next up previous contents
Next: References Up: Calibration Products Previous: Simulations of CCD Response

Mark Bautz
11/20/1997