1 UV_FITC Fit spherically symmetric, centered models through a UV table

        This task allows fitting of simple models directly from the visibil‐
    ities. The models are linear combinations of 2 radial distributions, as‐
    sumed  to  be  centered  on the current phase tracking center. Use tasks
    UV_CENTER and UV_SHIFT if necessary before fitting.

    A more flexible and more general fitting procedure is available  in  the
    UVT  task.  This  version  is  more suitable for plotting a fit over re‐
    binned visibilities.

    The type of the first radial distribution. Available types are
        NONE      No function to fit (for 2nd function usually)
        POINT     Point source
        GAUSS     Gaussian sources
        DISK      Disk
        RING      Annulus
        EXPONENT  Exponential brightness
        POWER‐1   B = 1/r
        POWER‐2   B = 1/r^2
        POWER‐3   B = 1/r^3
        PARABOLA  Parabolic brightness distribution

2 UVTABLE$
        TASK\CHARACTER "Input UV table"  UVTABLE$

    The UV table name.
2 CHANNEL$
        TASK\INTEGER "First and Last Channel to fit" CHANNEL$[2]

First and last channel to consider in the fitting process
2 FUNCTION_1$
        TASK\CHARACTER "First function"  FUNCTION_1$

    The type of the first radial distribution. Available  types  are  POINT,
    GAUSS,  DISK,  EXPONENT,  RING,  POWER‐1, POWER‐2, POWER‐3, PARABOLA and
    NONE
2 PARA1$
        TASK\REAL "Guessed parameters"   PARA_1$[3]

    The 1st function initial parameters: Total flux,  angular  diameter  (in
    radians), and inner diameter (for the RING function).
2 FUNCTION_2$
        TASK\CHARACTER "Second function" FUNCTION_2$

    The  type  of the second radial distribution. Available types are POINT,
    GAUSS, DISK, EXPONENT, RING, POWER‐1,  POWER‐2,  POWER‐3,  PARABOLA  and
    NONE
2 PARA_2$ TASK\REAL "Guessed parameters"   PARA_2$[3]

    The  2nd  function  initial parameters: Total flux, angular diameter (in
    radians), and inner diameter (for the RING function).
2 RESULT$
        TASK\CHARACTER "Output file"     RESULT$

    The name of the output file summarising the fit results. This file  con‐
    tains for each channel:
       channel number, velocity, flux, size, size2, flux, size, size2
    and  can  be  read  by a GREG\COLUMN command. A procedure (pr:uv_fit) is
    available to obtain plots from this file.

    In additions files named RESULTiii, where RESULT is the name of the pre‐
    vious  file,  and  iii the channel number, are created for each channel.
    This files contain the (optionally) binned data and the  fitted  values.
    A  procedure (PR:UV_FITC) is available to obtain plots from it. In addi‐
    tion GO UVALL uses these files for multi‐channel plots.
2 QRANGE$
        TASK\REAL "Range (meters) and number of UV points" QRANGE$[3]

    The UV range in meter and the number of points used for binning
2 LAMBDA$
        TASK\REAL "Starting Lambda"      LAMBDA$ 0.01

    The minimization control parameter. Use the default of 0.01  unless  the
    program does not want to converge.
2 AMPLITUDE$
        TASK\LOGICAL "Fit Amplitude or Real values" AMPLITUDE$  NO

    Fit  data  from real part or amplitude of the visibilities. Best results
    are normally obtained from the real part.
2 BINDATA$
        TASK\LOGICAL "Bin data before Fit ?" BINDATA$ YES

    Radially average data into bins specified by QRANGE$ before starting the
    fit. This improves considerably the speed of convergence.
1 ENDOFHELP














































