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2 NAME

The name to be printed on the right side of the dirty image and dirty beam
plots (with extensions .LMV and .BEAM).

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2 MAP__ANGLE

  MAP__ANGLE      Real

Position Angle of the direction which will become the apparent North in the
map. Used only if UV__SHIFT is YES.

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2 MAP__BEAM__STEP

  MAP__BEAM__STEP   Integer

Number of channels per synthesized beam plane.

A value of 0 means 1 beam plane for all channels.
N (>0) indicates N consecutive channels will share the same dirty beam.

A value of -1 can be used to compute the number of channels per beam plane
to ensure the angular scale does not deviate more than a fraction
of the map cell at the map edge. This fraction is controlled by
variable MAP__PRECIS (default 0.1)

Default is -1.

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2 MAP__CELL

      MAP__CELL[2]    Real

The map pixel size [arcsec]. It is recommended to use identical values in X
and Y.  A sampling of at least 3 pixel per beam is recommended to ease the
deconvolution. Enter 0,0 to let the task find the best values.

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2 MAP__CONVOLUTION

    MAP__CONVOLUTION    Integer

Select the desired convolution function for gridding  in  the  UV  plane
Choices are
.nf
        0    Default (currently 5)
        1    Boxcar
        2    Gaussian
        3    Sin(x)/x
        4    Gaussian * Sin(x)/x
        5    Spheroidal
.fi
Spheroidal functions is the optimal choice. So we strongly discourage use
of any other convolution function.

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2 MAP__DEC

  MAP__DEC      Character string

New Declination of map phase center in Degrees, sexagesimal notation allowed.
Used only if MAP__SHIFT is YES.

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2 MAP__FIELD

  MAP__FIELD[2]     Real

Field of view in X and Y in arcsec.  The field of view MAP__FIELD has
precedence over the number of pixels MAP__SIZE to define the actual
map size when both are non-zero.

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2 MAP__POWER
.ti +4

  MAP__POWER[2]     Integer
  
Maximum exponent of 3 and 5 allowed in automatic guess of MAP__SIZE.
MAP__SIZE is decomposed in 2^k 3^p 5^q, and p and q must be less or
equal to MAP__POWER.

Default is 0: MAP__SIZE is just a power of 2. A value of 1 allows
approximation of any map size to 20 %, while a value of 2 allows
10 % approximation. Fast Fourier Transform are slightly slower with
powers of 3 and 5, but limiting the map size can gain a lot in the
Cleaning process (which can scale as MAP__SIZE^4). 


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2 MAP__PRECIS

  MAP__PRECIS    Real

Maximum mismatch in pixel at map edge between the true synthesized beam
(which would have been computed using the exact channel frequency) and the
computed synthesized beam with  the mean frequency of the channels sharing
the same beam. This is used (with the actual image size) to derive the
actual number of channels which can share the same beam, i.e. the
effective value of MAP__BEAM__STEP when MAP__BEAM__STEP is -1.

Default is 0.1

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2 MAP__RA

  MAP__RA       Character string

New Right Ascension of map phase center, in hours, sexagesimal notation allowed.
Used only if MAP__SHIFT is YES.

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2 MAP__ROBUST

  MAP__ROBUST     Real

Robust weighting factor. A number between 0 and +infty.  Only used if
MAP__WEIGHT is set to UNIFORM or ROBUST.

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2 MAP__ROUNDING

  MAP__ROUNDING     Real 

Maximum error between optimal size (MAP__FIELD / MAP__CELL) and rounded
(as a power of 2^k 3^p 5^q) MAP__SIZE to round by floor (thus limiting
the field of view), instead of ceiling (which guarantees a larger 
field of view, but leads to bigger images).

Default is 0.05.  
  
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2 MAP__SIZE

  MAP__SIZE[2]      Integer

Number of pixels in X and Y. It should preferentially be a power of two,
(although this is not strictly required) to speed-up the FFT. MAP__SIZE*MAP__CELL
should be at least twice the size of the field-of-view (primary beam size
for a single field). Enter 0,0 to let the command find a sensible map size.

MAP__SIZE is not used if MAP__FIELD is non zero.

Odd values are forbidden. 

Default is 0,0, i.e. UV__MAP will guess the most appropriate values
which depend on MAP__ROUNDING and MAP__POWER.


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2 MAP__SHIFT

  MAP__SHIFT        Logical

Logical variable indicating whether map center (i.e. phase tracking center)
or orientation should be changed.

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2 MAP__TAPEREXPO

  MAP__TAPEREXPO    Real

Taper exponent. The default is 2 (indicating a Gaussian) but smoother or
sharper functions can be used. 1 would give an Exponential, 4 would be getting
close to square profile...

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2 MAP__TRUNCATE

  MAP__TRUNCATE    Real

Mosaic truncation level in PerCent.  Default value is 0.2. Current value can be
overriden by option /TRUNCATE in commands UV__MAP or PRIMARY.

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2 MAP__UVTAPER

  MAP__UVTAPER[3]  Real

Parameters of the tapering function (Gaussian if MAP__TAPEREXPO = 2):
major axis at 1/e level [m], minor axis at 1/e level [m], and position angle [deg].

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2 MAP__UVCELL

  MAP__UVCELL   Real

UV cell size for robust weighting [m].  Should be of the
order of half the dish diameter (7.5 m for PdBI), or smaller or even larger.
It controls the beam shape in Robust weighting.

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2 MAP__VERSION

  MAP__VERSION  Integer

[EXPERT Only] Code indicating which version of the UV__MAP and UV__RESTORE algorithm should
be used. 0 is optimal. -1 is the "historical" (pre-2016) version. 1 is an intermediate
version used during multi-frequency beams development.

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2 MAP__WEIGHT

  MAP_WEIGHT    Character
  
Weighting mode: Natural (optimum in terms of sensitivity) or robust
(usually lower sidelobes and higher spatial resolution) weighting.
Use LET MAP__WEIGHT NATURAL for natural or LET MAP__WEIGHT ROBUST for robust weighting.

The actual weighting methods implemented are Natural and Robust
weighting. Robust weighting gives the natural weight to UV cells whose
natural weight is lower than a given threshold. In contrast, if the natural
weight of the UV cell is larger than this threshold, the weight is set to
this (uniform) threshold. The UV cell size is defined by MAP__UVCELL and
the threshold value is in MAP__ROBUST.

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2 MCOL

  MCOL[2]   Integer

First and Last channel to image. Values of 0 mean imaging all the planes.

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2 WCOL

  WCOL      Integer

[Obsolescent] The channel from which the weight should be taken.  WCOL set to 0 means
using a default channel. WCOL has no real meaning in all cases where
more than one beam is computed for all channels.

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2 Old__Names:
.nf
 NAME        [       ]  Label of the dirty image and beam plots
 UV__TAPER    [m,m,deg]  UV-apodization by convolution with a Gaussian
 WEIGHT__MODE [       ]  Weighting mode (NA|UN)
 UV__CELL     [m, ??  ]  UV cell size and threshold for Robust weighting
 MAP__FIELD   [ arcsec]  Map field of view
 MAP__CELL    [ arcsec]  Map cell size
 MAP__SIZE    [ pixels]  Map size in pixels (if MAP__FIELD is zero)
 MCOL        [       ]  First and Last channel to map
 WCOL        [       ]  Channel from which the weights are taken
 CONVOLUTION [       ]  Convolution function (5)
 UV__SHIFT    [       ]  Change the map phase center or map orientation?
 MAP__RA      [       ]  RA of map phase center
 MAP__DEC     [       ]  Dec of map phase center
 MAP__ANGLE   [    deg]  Map position angle
 MAP__BEAM__STEP [     ]  Number of channels per synthesized beam plane
.fi

.ti -4
2 convolution

  Older variable name for MAP__CONVOLUTION

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2 uv__taper

  Older variable name of MAP__UVTAPER

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2 uv__cell

  Older variables for MAP__UVCELL (uv_cell[1]) and MAP__ROBUST

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2 taper__expo

  Older variable name for MAP__TAPEREXPO

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2 weight__mode

  Older variable name of MAP__WEIGHT






