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Program operation

The shell program SPECTRAL asks the user a few questions to establish the locations of the needed data files (described below), runs SPECMAT if necessary to create the response matrix, and then runs SPECNLYZ to fit a spectrum.

Two default files are expected to be found: ``cones.default'', which gives the default energy bands, acceptance cones, and area fudge factors for pulsar analysis, and ``fit.default'', which gives the starting values for several fitting parameters. SPECTRAL first searches for these files in the current directory. If they are not found there, it checks the default system directory $EGRET_DIR/lib/spectral. If that fails, then SPECTRAL will prompt for new file names. Users who wish to customize these files should copy the system default files to their own directories.

First, SPECTRAL asks if the source to be analyzed is periodic or DC. The former answer will lead to pulse-phase spectroscopy.

Next, SPECTRAL will ask which type of events are to be analyzed, Class A or A+B+C. This ensures that the proper calibration files are used. When Class A events are selected, Class C events can also be analyzed as a separate energy channel. It appears that the Class C calibration files are incorrect at this time, so this channel should be ignored.

Next, if the source is periodic, SPECTRAL will if the user wishes to use an external background file. If so, it will prompt for the name of the file.

Next, SPECTRAL will ask for the name of a data file. This should be either a PULSAR output file in SELECT format or a PSRSPEC output file.

SPECTRAL checks for the existence of files containing the response matrix. The names of these files are based on the data file name. For instance, if the PULSAR file is foobar, then the response matrix file should be resp.foobar.

If this file is found, the program SPECNLYZ will be started. The program will give you a few messages as it reads in the data files; this will take a little while. Then you will see the main menu.

Commands: Fit,Counts,Rebin,Parameters,Write,Display,Top,Spawn,Help,Quit
Using the program from here is fairly simple. The options will be discussed briefly below.

If the matrix and background files don't exist, SPECTRAL will run SPECMAT to create them, and then it will run SPECNLYZ. Some more input files are needed to run SPECMAT.

First, SPECTRAL checks for the existence of files for the the point-spread function, class-A sensitive area, class-C sensitive area, and energy resolution. If any of these is not found, the user will be prompted for the correct name.

next up previous
Next: Input Files; Acceptance Cones Up: How to Use SPECTRAL Previous: How to Use SPECTRAL