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BASE

        LAS\BASE [Deg] [/PLOT [Ipen]] [/INDEX] [/OBS] [/CONTINUUM [flux]]
        LAS\BASE SINUS Amplitude Period Phase [/PLOT [Ipen]]
        LAS\BASE LAST [/PLOT [Ipen]]

    When working on single spectra, BASE copies R  into  T,  then  subtracts
    from  R a polynomial baseline of degree Deg, or a sinusoidal baseline if
    the first argument is SINUS. Zones defined by the SET WINDOW command are
    not  used to fit the baseline. The T content may be recovered with SWAP.

    BASE SINUS Amplitude Period Phase
    (Phase is in the same unit as the period, usually km/s or MHz)  Subtract
    a  sinusoid.  Minimization will be done including also a linear baseline
    in addition to the sinusoid.

    BASE LAST
    Use the last determined baseline instead of computing a new one. It  can
    be  useful  to find a baseline from one backend and apply it to another.
    This also applies for sinusoidal baselines.

    BASE /PLOT
    Plot this baseline after the minimization, using the Ipen-th pen proper-
    ties. The pencil 2 (red at startup) is used by default.

    BASE /INDEX
    Subtracts  a  baseline to all records that have been loaded. This option
    is not needed if SET ACTION INDEX. /PLOT and /INDEX options  are  incom-
    patibles.

    BASE /OBS
    indicate  that  the baseline is to be fitted to the current R buffer ob-
    servations. This option is not needed if the action level  is  OBS  (de-
    fault). /OBS and /INDEX are incompatible.

    BASE /CONTINUUM
    Divide  the spectrum by the baseline rather than subtracting it and mul-
    tiply by the average flux. This is useful to keep the  continuum  level,
    when  continuum  is  present  and variations of atmospheric emission are
    properly subtracted out by fast enough switching.  This is of course the
    case  for  correlation spectra (e.g. coming from an interferometer). The
    continuum level will be adjusted to the value of the argument 'flux', if
    present; e.g. /CONTINUUM 1.0 will produce a spectrum of line-to-continu-
    um ratio. BASE /CONTINUUM does not work with BASE LAST or BASE SINUS.


Gildas manager 2011-09-07