SOLVE AMPLITUDE

 

        CLIC\SOLVE  AMPLITUDE   [/PLOT]   [/BREAK   ...]    [/POLYNOMIAL...]
    [/WEIGHT]

    This will fit a mathematical function into the  measured   amplitude  of
    the  sources  in  the current index (presumably calibrators).  This data
    must have been selected and plotted in axes :  SET  X  TIME  and  SET  Y
    AMPLITUDE  for  the  baselines  and  bands of interest, specified by the
    corresponding SET commands.  The calibration function is kept in memory.
    Command  STORE  should be used next to store this function in the header
    of source observations, after a  change  in  the  index  to  select  the
    appropriate scans.

    In antenna mode the averaged phase and amplitude closures are  computed,
    as well as their standard deviations. The phase closures should be close
    to zero, while the amplitude closures should be close  to  100%.  Strong
    deviations  of  amplitude  closures  from  100%  are  an  indication  of
    amplitude loss on long baselines, due to phase decorrelation during  the
    time  averaging.  The  fit  then shows strong systematic errors; if this
    occurs, baseline based calibration of the amplitudes might be preferred.

    Option /PLOT will plot the fitted curve over the data.

    Fitted curves may be of two kinds:

  -  Cubic splines (the default).  By default  knots  are  regularly  spaced
    with   an   interval   between   knots   set  by  the  SET STEP command.
    Additional knots may be introduced with the  option:  /BREAK  kind  time
    [kind  time  ...]  a  break introduced at abscissa 'time' ; 'kind' is an
    integer in the  range 0-3; 0 means that a discontinuity will be present,
    1  that  the  first  derivative  will  be   discontinuous,  and  so  on.
    Several  breaks  may  be introduced; the program will detect an error if
    too   many   breaks  are  introduced,  compared  to  the density of data
    points.

  -  Polynomial curves may  be  used  instead.   For  this  the  option  is:
    /POLYNOMIAL  [degree]  indicating  the degree of the polynomial (default
    0).


    Normally the data points are all assigned the same weight  for  the fit.
    With   option  /WEIGHT,  the data points are weighted according to their
    errors.   Errors  are  set   to   the   statistical   errors   for   the
    amplitudes.