1 UV_SINGLE Obsolete (See UV_SHORT instead)
        UV_SINGLE

    CAUTION: This task is obsolete. It is keeped because it is still used by
    the ALMA simulator.

    This task prepares one or more (for mosaics) UV tables of short spacings
    from  a   single‐dish  table  of  spectra  (as produced by CLASS command
    GRID).  This table may later be merged to an  interferometer  UV  table.
    Two major steps are performed for this:
      ‐ Creation of a "well behaved" map from the spectra.
      ‐ Extraction of UV spacings from this map.

    The  "well  behaved" map is obtained by linear operations (convolutions)
    from the original spectra, in an optimum way from signal to noise  point
    of  view.  The map is extrapolated smoothly towards zero at the map edge
    in order to avoid further aliasing in the Fourier  transform  operations
    required  in  step 2. This extrapolation has a scale length of twice the
    single‐dish beam, in order to avoid spurious Fourier components.

    To obtain it, UV_SINGLE performs the following operations:
      ‐  Resampling (in space) of the original spectra on a regular grid  by
        convolution  with  a  small  (typically 1/4 of the single‐dish beam)
        gaussian convolving kernel. In this process, the weights of individ‐
        ual spectra is carried on a weight map.
      ‐  Extrapolation by zero outside the convex hull of the mapped region
      ‐   Convolution  of the result by a gaussian twice as wide as the sin‐
        gle‐dish beam.
      ‐  Within the convex hull of the mapped region, the  smoothed  map  is
        replaced by the original map.

    From this map, UV_SINGLE computes one or several UV tables (one for each
    pointing center in case of a mosaic) in the following way:
      ‐  Fourier transform of the single dish map
      ‐  Division by the Fourier transform of the single dish  beam,  up  to
        a maximum spacing (SD_DIAM$, in meters)
      ‐  Inverse Fourier transform to  the  image  plane
    and then for each pointing center
      ‐   Multiplication of the  image  by the primary beam of the interfer‐
        ometer elements
      ‐  Fourier transform back to the UV plane.
      ‐  Creation of the UV table, with a given weight SD_WEIGTH$ and an ap‐
        propriate calibration factor to Janskys SD_FACTOR$

    Both the single‐dish and the interferometer antennas are assumed to have
    gaussian beams (SD_BEAM$ and IP_BEAM$, in radians).

2 TABLE$

    The table of spectra produced by CLASS command GRID.

2 MAP$

    The name of the single dish map which will be produced (as an intermedi‐
    ate result) by UV_SINGLE

2 XCOL$

    The  number of column containing X offsets. For tables produced by CLASS
    command GRID, XCOL$ should be 1.

2 YCOL$

    The number of column containing X offsets. For tables produced by  CLASS
    command GRID, YCOL$ should be 2.

2 WCOL$

    The  number  of column containing the weights of the spectra. For tables
    produced by CLASS command GRID, WCOL$ should be 3.

2 MCOL$

    The first and last column to be mapped. For tables produced  by  command
    CLASS,  MCOL$[1] should be 4 and MCOL$[2] can be set to 0 to process all
    channels.

2 WEIGHTDE$

    The weighting mode. Use ’NA’ for Natural weighting.

2 TOLE$

    The tolerance in position. Spectra differing by less  than  this  amount
    will be added together prior to gridding.

2 MINWEIGHT$

    The  minimum  weights  under  which  a  given point in the map should be
    filled by the smooth map rather than by the gridded (original) map.  De‐
    fault value of 0.01 and 0 is appropriate.

2 UV_TABLE$

    Generic  output  UV  table  name,  without extension. When the number of
    fields NF$ is larger than 1, UV_SINGLE will add ‐’I’ to the generic name
    to create a UV table for field I.

2 DO_SINGLE$

    Logical value, should be YES except for test purposes.

2 SD_DIAM$

    Useful diameter of the single dish, in meters.  No spacing  higher  than
    SD_DIAM$ is generated.

2 SD_BEAM$

    Half‐power beam width of the single dish antenna, in radians.  The  beam
    is assumed to be gaussian.

2 SD_WEIGHT$

    Total weight of the generated visibilities.  If set to 0, it will be set
    to 10**‐6/sigma**2, where  sigma  is  the  r.m.s.  of  the  zero‐spacing
    value (total flux) in janskys.

2 SD_FACTOR$

    Multiplicative calibration factor; it is used to convert from the single
    dish map units (e.g., main‐beam brightness temperature) to janskys.

2 DO_PRIMARY$

    Logical value, should be YES except for test purposes.

2 IP_BEAM$

    Half‐power beam width of the interferometer antennas, in  radians.   The
    beam is assumed to be gaussian.

2 MOSAIC_RA$

    The  Right  Ascension (HH:mm:ss.sss) of the center of the interferometer
    field (center of mosaic or pointing center of the interferometer  for  a
    single field).

2 MOSAIC_DEC$

    The  Declination  (Sdd:mm:ss.sss)  of  the  center of the interferometer
    field (center of mosaic or pointing center of the interferometer  for  a
    single field).

2 NF$

    Number  of  fields  to  be created. NF$ should be equal to the number of
    fields used in the mosaic at the interferometer. NF$ is 1 for  a  normal
    observation.

2 DRA$

    Projected  offsets  on  the  sky  of  the pointing centers of the mosaic
    fields parallel to the right ascension axis, with respect to the  mosaic
    center defined by MOSAIC_RA$ and MOSAIC_DEC$.

2 DEC$

    Projected  offsets  on  the  sky  of  the pointing centers of the mosaic
    fields parallel to the declination axis, with respect to the mosaic cen‐
    ter defined by MOSAIC_RA$ and MOSAIC_DEC$.

1 ENDOFHELP



































