SOLVE SPIDX

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SOLVE SPIDX

            CLIC\SOLVE SPIDX [NOREFERENCE] [BEST  n]  [REAL]  [/RESET]  [/OUTPUT
        file]

        Calculate  the  spectral  indexes of the sources in the current index or
        the antenna efficiencies (Jansky to Kelvin) if the source spectral index
        is known.  The command can also be used to bootstrap source spectral in-
        dexes from a known source.

        It should be used before computing any amplitude calibration, on an  in-
        dex  covering  a  reasonably short time interval to avoid possible effi-
        ciency variations.

        The commands should be used in the following way:

            - The command SET SPIDX is used to define the spectral index of one,
            or  several  of the sources in the current index for which the spec-
            tral index is known. Frequencies and dates may be specified.

          - Then the command SOLVE SPIDX will use the sources of known  spectral
            index  (optionally with matching frequencies and dates) to determine
            the efficiencies for all antennas. SOLVE SPIDX now gives the  decor-
            relation  factor  relative  to  the  efficiencies logged in the scan
            headers (assumed to be the standard single-dish efficiencies).

          - SOLVE SPIDX then uses these antenna efficiences to compute the spec-
            tral  indexes  of  all  other  sources.  IF  the keyword "BEST n" is
            present, the n antennas giving the highest fluxes will be  used  for
            averaging  (n  is 1 to the number of available antennas). Default is
            n=3.

          - The command SHOW SPIDX will give the current  spectral  index  list.
            The  reference  sources are listed with a "FIXED" keyword, while the
            spectral indexes determined by SOLVE SPIDX are listed as "FREE".

          - SOLVE SPIDX /RESET can be used to  reset  the  spectral  index  list
            (i.e.  remove  from the list all sources whose spectral index is not
            fixed) before processing.

          - SOLVE SPIDX /OUTPUT file [NEW] will produce an output file with  the
            results  printed  for  each  antenna.  Use keyword NEW to open a new
            file.

          - The command STORE SPIDX will store the spectral  indexes  and  effi-
            ciencies in the headers of the observations in the current index.

        If no reference sources are available, the keyword NOREFERENCE should be
        given, and the default efficiencies stored in the data  header  will  be
        used (step 2 in the above list is bypassed).

        The keyword REAL forces SOLVE SPIDX to use the real part of the visibil-
        ities instead of the amplitude to derive the  antenna  efficiencies  and
        source  spectral indexes. This is only for test purposes and must not be
        used without asking an expert.