SOLVE BASELINE

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SOLVE BASELINE

            CLIC\SOLVE BASELINE [/OFFSET b1 dx1 dy1 dz1 b2  ...]
            [/SEARCH  range  interval]  [/POLYNOMIAL  degree]  [/RESET]  [/PLOT]
        [/SIN]

        This  uses  a  linear method to determine baselines. The baselines to be
        determined must have been selected by the SET BASELINE command, and  the
        data  plotted;  plot  axes must have been previously selected by : SET X
        HOUR_ANGLE DECLINATION and SET Y PHASE. With SET ANTENNA in  action  the
        antenna  position offsets are directly fitted to the antenna phases, en-
        suring baseline closure.

        The fitting should work only if the starting values are  within  half  a
        wavelength  in  any  direction of the true values. Use option /OFFSET to
        correct the phases for an offset (dx1,dy1,dz1)  in  baseline  b1  before
        fitting.   This  is needed if the baseline was wrong by more than half a
        wavelength. Offsets are to be given in meters.

        The results are given as offsets in  meters   to   be   added   to   the
        baseline  used  for  data  acquisition (which may be read by SIC\EXAMINE
        BASELINE).  The total fitted baseline is also given in meters,  as  well
        as  the  rms  of  the residuals in phase units.  Two sets of offsets are
        given:  the first set (dx, dy, dz) are the offsets with respect  to  the
        antenna  positions actually used, while the secoond set (DX, DY, DZ) are
        with respect to the standard antenna coordinates (the default values  in
        OBS).

        The  /SEARCH option  enables  an  automatic  search  with  starting off-
        sets  scanning a 3-d box in dx, dy, dz, by steps of half a wavelength in
        the  three  directions.   The arguments range and interval are in meters
        (scanning  is from  -range/2 to +range/2, default -0.005 to 0.005).  On-
        ly the solution with the minimum rms is kept.

        With  option /POLYNOMIAL degree, and  if  SET  X  TIME  is  used  in ad-
        dition of HOUR_ANGLE and DECLINATION, a polynomial function of  time  is
        included in the phase function being fitted.  The degree may range  from
        0 (the default) to 3.  In that case command RESIDUALS will also plot the
        residuals as a function of time.

        The /RESET option resets the solutions in memory.

        The /PLOT option allows to plot the data used for fitting.

        Use  command  RESIDUALS  BASELINE  to  display  the fit residuals (phase
        should be constant). Use later command PRINT BASELINE to create a proce-
        dure file (named CLIC-BASELINE.OBS) containing the antenna position off-
        sets.  This procedure file may be executed by the observing program  OBS
        on the control computer bure01.

        If  one  specify  elevation  as  an  additional  X  variable (e.g. SET X
        HOUR_ANGLE DECLINATION TIME ELEVATION), then an additional parameter  is
        fitted:  the  offsets  between elevation and azimuth axes (or rather the
        differences between antennas). These differing offsets result in a phase
        effect  proportional  to the cosine of elevation. In antenna mode, these
        offsets are given for each antenna in meters.  In  baseline  mode,  only
        differences  are  computed.  To  further correct for this effect use the
        command MODIFY AXES. One can optionnaly fit a sinus instead of a cosinus
        in this specific case using option /SIN.