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Up: 5.2.1 ACIS-supplied Tools
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Event Browser (EB) is an IDL widget application which is used to manipulate x-ray event lists. EB provides users with a graphical user interface for doing such things as selecting data files, filtering event lists in numerous ways, and displaying and printing results.
A particular strength of Event Browser is the ability to see the effect of changing selection criteria immediately. The selection criteria possible are many, and are very oriented to the physically important characteristics of the CCD and the AXAF HRMA imaging. Event Browser enables selection of events based on position, event energy, event grade, CCD chip, CCD amplifier and time.
Event Browser also offers a range of display capabilities to reveal characteristics of the dataset being examined. These include images of the spatial distribution in two dimensions, spectra (histograms of number of events vs. energy), light curves (histograms of number of events vs. time), and general two property comparisions (any two characteristics of an event [energy, time, x, y, grade] as a scatter plot).
Spectra can be converted from detector Data Number (DN) values into X-ray energy in eV to facilitate combination of data from different CCD amplifiers.
Images can be formed from data from multiple CCDs by combining them into the detector focal plane coordinate system ``AXAF-ACIS-2.2'', as defined by Jonathon McDowell's (ASC) ``ASC Coordinates, Rev 4.0''. This allows images to be produced which look like panoramic views of the sky, and to facilite reduction of dispersed spectra made by the gratings, which may fall on up to six CCD chips. Figure 5.2 shows the locations of the ACIS CCD chips in the ASC DETX/DETY focal plane coordinate system.
Regions of interest in the spatial, spectral and temporal domains can be selected interactively based on the image, spectral and light curve displays to further apply improved filtering to the data products.
Some data analysis capabilities such as simple model fitting, centroiding and plots of radial surface brightness are built into Event Browser. For more extensive analysis capability, spectra, light curves, images and other Event Browser results can be saved in the form of FITS files for export to other advanced analysis programs.
John Nousek
