Creating Simulated Datasets with XSPEC

We do not yet have a script to create simulations. The following recipe works:

1.   Create a shell script to provide inputs to xspec. The following is an example used to create the 0.4 keV pha files for 61 Cyg:

   #! /bin/tcsh -f
   
   echo "mo ray" 
   echo "0.4 1.0000E-02  8.0000E-03  8.0000E-03 64.00       64.00"
   echo "1.0     -1.0000E-03      0.          0.       5.000       5.000"
   echo "0.     -1.0000E-03      0.          0.       2.000       2.000"
   echo "1e-3      1.0000E-02      0.          0.      1.0000E+24  1.0000E+24"
   
   
   set comlist = `cat $1`
   
   foreach file ($comlist)
   
   echo "fakeit none"
   echo "new_resp.fits"
   echo " hri_arf.fits" 
   echo "y" 
   echo "\n"
   echo $file 
   echo "6688,  1.0000 , 1.0000 , 0."
   
   end

   The script will output the model parameters, ie. the first 5 lines of the script. The script will then read in a list of file names and output a set of instructions to xspec to create multiple fake pha files. If the list of file names is as follows:

   pha1
   pha2

   the output of the script will be:

   mo ray
   0.4 1.0000E-02  8.0000E-03  8.0000E-03 64.00       64.00
   1.0     -1.0000E-03      0.          0.       5.000       5.000
   0.     -1.0000E-03      0.          0.       2.000       2.000
   1e-3      1.0000E-02      0.          0.      1.0000E+24  1.0000E+24
   fakeit none
   new_resp.fits
    hri_arf.fits
   y
   \n
   pha1
   6688,  1.0000 , 1.0000 , 0.
   fakeit none
   new_resp.fits
    hri_arf.fits
   y
   \n
   pha2
   6688,  1.0000 , 1.0000 , 0.

2. Run xspec to generate fake pha files. If the output of the script in item 1 was piped to a file called xinput, run xspec with the command

   > xspec xinput

   The result will be 2 fake pha files, pha1.pha and pha2.pha. A larger number will be needed to obtain a statistically meaningful result!
3. Obtain the hardness ratios of the fake data files. The following is an IRAF script to do this in an automated way.

   procedure ratio (scanfile,output)
   
   char *list
   char scanfile {prompt ="Enter simulation list"}  #image list
   char output {prompt="Output file"}
   
   begin
   
   #declare local variables
   
   char spect,outfile
   real h,r,e,s
   
   list=scanfile
   outfile=output
   
   #read file
   
   while (fscan (list,spect) !=EOF){
   
   fstatistic(infile=spect,colname="counts",rows="1-4")
   s=fstatistic.sum
   fstatistic(infile=spect,colname="counts",rows="5-15")
   r=s/h
   e=r*(s**(-1)+h**(-1))**(0.5)
   print(h,s,r,e, >> outfile)
   
   }
   end

   The parameters for this script are a file containing a list of fake pha files and the name of the output file. The output file is an ascii file with columns containing the number of ``hard'' counts (channels 5-15 in this case), the number of ``soft'' counts (channels 1-4), the ratio soft/hard and the ratio error.

4. Read the file with counts and ratios into IDL or other plotting/analysis package and plot a histogram.