We shall start with a simple example based on very old data, an EXOSAT observation of GX301-2. First we read in the data :
XSPEC version: 12.5.1
Build Date/Time: Mon Aug 3 13:17:56 2009
XSPEC12>data file1.pha
1 spectrum in use
Spectral Data File: file1.pha Spectrum 1
Net count rate (cts/s) for Spectrum:1 3.586e+01 +/- 2.466e-01 (50.6 % total)
Assigned to Data Group 1 and Plot Group 1
Noticed Channels: 1-64
Telescope: EXOSAT Instrument: ME Channel Type: PHA
Exposure Time: 2100 sec
Using Background File back1.pha
Background Exposure Time: 3320 sec
Using Response (RMF) File resp1.rsp for Source
This dataset has associated background and response files which have been read in automatically because their names are given in file1.pha by the BACKFILE and RESPFILE keywords. If these keywords were not set, we could load the associated files using :
XSPEC12>back back1.pha Net count rate (cts/s) for Spectrum:1 3.586e+01 +/- 2.466e-01 (50.6 % total) XSPEC12>resp resp1.rsp Response successfully loaded.
Generally the best first step is to look at the spectrum :
XSPEC12>cpd /xs XSPEC12>plot data XSPEC12>setp energy XSPEC12>plot
The first command sets the plotting device to the X-window server. The third command switches the x-axis from channels to energy. If you want it in wavelength then use setp wave. Note that the plot command remembers the option from its last invocation.
