rmsspec

 RMS N1 N2 N3 METHOD WEIGHTS -- Work out RMS variability spectrum

 Works out RMS spectrum from a time series of spectra
 Output slot contains :  rms = sqrt ( < (f-)^2 > )

 Danny Steeghs @ soton mar 2000
 
 Parameters: 
     
  N1    -- Slot number of first spectrum to average
  N2    -- Slot number of last spectrum to average
  N3    -- Slot in which to put results
  METHOD - Averaging method. At present supports
           U  -- Unit weights
           D  -- Dwell weights
           R  -- Response weights
           V  -- Variance weights

  WEIGHTS -- a file of weights that multiply whatever weights are generated
             by method.  to ignore. The weights should be for every
             spectrum regardless of selection.

 Response weights are proportional to the local ratio of COUNTS/FLUX
 and thus effectively add the counts together (optimum for photon
 counting data). Variance weights use a single value equal to the
 mean Signal/noise**2 for each spectrum.

 Selection is done. 

 The spectra must have equal numbers of pixels, but no other properties
 in common. A warning is given if the wavelength scales differ but
 averaging still goes ahead

This command belongs to the class: time_series