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*imcalc* - Obtain a background subtracted image for ROSAT PSPC Data

An energy filter and blocking factor will be applied to match those of the background map. Use the ROSAT broad band background which is a $512\times 512$ array file at 1/30 the *.qp file resolution, and contains data from PI bins 7-240.

input files: xdata$rp110590.qp; xdata$rp110590_bk1.imh

output file: rp90_a.imh

  xr> ximages 
  xi> imcalc  
  input file ('-' for STDIN) or imcalc commands:  -              # Interactive mode 
  IMC)  rp90_a.imh = xdata$rp110590.qp[bl=30,pi=7:240] - xdata$rp110590_bkl.imh 
                              # Select same size and channels as the background map 
                                                     # and subtract the background 
   IMC) quit                             # To exit the interactive mode and imcalc

The output file is a $512\times 512$ array containing data in the broad PSPC band.