MODSOURCE

##
MODSOURCE

            [WEEDS\]MODSOURCE   MODFILE  ANTSIZE  [/TCONT  TCONT]  [/OPACITY  I]
        [/KEEPCONT] [/VERBOSE]

        Model the emission of a source assuming local thermodynamic  equilibrium
        (LTE). The model paramaters (column density, kinetic temperature, source
        size, line width and velocity offset for each  species)  are  read  from
        MODFILE.  The  modeled  brightness temperature is stored in the TB_MODEL
        memory. For convenience the current spectrum is also stored in a memory,
        OBS,  so one can easily overplot the result of the model on the observed
        spectrum. See the documentation manual for more details on the  computa-
        tion.

        Arguments:
          MODFILE     the  name  of the file containing the parameters. The file
                      must have one line per species with at least  six  columns
                      containing respectively:

                      1) The species name
                      2) The column density for this species in cm-2
                      3) The excitation temperature in K
                      4) The source size in arcsec
                      5) The offset velocity from the source VLSR, in km/s
                      6) The line FWHM in km/s

                      One  additional  column  may be used to select a different
                      origin for each species:

                      7) The origin of this species (e.g. JPL or CDMS). If  emp-
                      ty, species with any origin are selected.

                      The following options may be used at the end of the line:

                      /ABSORPTION   If  this option is set, the component is as-
                      sumed to be a foreground layer.

                      /PARTFUNC Q  Set the log10 of the  partition  function  at
                      the excitation temperature to Q. If not set, the partition
                      function values (log-log interpolated/extrapolated at  the
                      excitation  temperature)  from  the  selected database are
                      used.

                      Lines that start with a "!" are treated as comments.

          ANTSIZE     the antenna size in meters

        Options:
          /TCONT      set the continuum level to TCONT, in K. The value  can  be
                      scalar (one value for the whole frequency range) or an ar-
                      ray name (same size as RY, one value per channel). Default
                      is 0.

          /OPACITY  I  store  the  opacity of the Ith component in the TAU_MODEL
                      memory. Components are numbered in the same  order  as  in
                      MODFILE, starting from 1.

          /KEEPCONT   do not remove the continuum from the final spectra.

          /VERBOSE    print  partition  function,  line frequencies, upper level
                      energies and degeneracies, Einstein coefficients and opac-
                      ities at the line centers.