WRITING SPECTRUM AND SRM FILES FOR SEPARATE DETECTORS WITH NATIVE ENERGY BINS    
   4-Jan-2011

Native energy bins are the boundaries of the detector channels in keV.  Native bins are approximately
.33 keV wide for the front detectors, but because the gain and offset vary, each detector has 
slightly different native energy bins.  

Using single detector native energy bins preserves the highest fidelity of the detector resolution.  
When detectors are combined, or data is binned to arbitrary energy bins, some interpolation is required.  
Analyzing fine structure in the solar spectrum, such as the Iron line at 6.7 keV, requires the finest 
resolution available.

Spectrum and SRM files for separate detectors with native energy bins are written via the routine
hsi_spectrum_sep_det_files.  This widget calls that routine.  hsi_spectrum_sep_det_files can be called from
the command line as well.  Please see the header of that routine for calling arguments and more explanation.

The detector selection shown in this widget defaults to the values currently in the 
spectrum object, but can be changed here.  The time interval for the files is the current Spectrum Time 
Interval from the spectrum object.  Any other parameters already set in the spectrum object will be used
(if compatible with file-writing).

We want all of the separate detector files to have the same number of energy bins (for comparison in 
OSPEX).  Since native energy bins are different for each detector, the maximum energy will be different for 
each detector.  The software examines the native energy bins for every front detector (not just the 
ones you've selected currently), and finds the minimum number of bins, NBIN,
needed such that every detector's bins will reach or exceed your selected maximum energy.

When you click the 'Write FITS files' button, the spectrum object does the following for each selected 
detector, 
  - sets the correct detector
  - sets the energy binning to the NBIN native energy bins between the selected min and max energy
  - calls the spectrum filewrite routine to write the spectrum FITS (and SRM if requested) file
  - exits the widget
  
Note that when it's done, the spectrum object has been altered and now reflects the settings used for the
last file written.

If you select the Plot option, an observing summary plot and a spectrum and time profile for each detector
will be displayed in the hessi GUI plotman interface.  You can recall them via the Window_Control button.