Private parameters for program NPLOT
This document contains an overview of the parameter interface of the program NPLOT. The program also uses a number of public interfaces; references to these are also listed. show parameters that The remainder of the document describes the individual parameters in alphabetical order. This description centers on the Help texts, which have been designed to guide the user to the proper choice at each junction, even if his knowledge of the overall workings of the program is only superficial.
See also:
Prompt: ONE position-angle map: grp.fld.chn.pol.0.seq
Expected input: Character *32: 1 value
Select a .WMP-file image holding polarisation position angles. If the image you specify contains anything else, your plot will be garbage.
The .WMP-file indices are:
group.field.channel.polarisation.type(=0).sequence_number
Prompt: Annotation text, up to 80 characters in double quotes
Expected input: Character *80: 1 value
This text will be displayed on all plots for this NPLOT run until you change it
Prompt: Area centre (l,m) and width (dl,dm) in grid units
Expected input: Integer: 1 to 4 values
Specify an area of a map:
l,m grid coordinates of area centre: 0,0 is the map centre,
increasing to the upper right (i.e. with DEcreasing
right ascension and INcreasing declination)
dl,dm area width and height
Prompt: Axis annotation style
Expected input: Character *24: 1 value
Select ONE style of axis annotations:
NONE no annotation (only pixel coordinates)
Relative quasi-Cartesian coordinates:
LM l, m in arcsec with respect to map centre
(or annotation for UV-plane plots)
DLM l, m in arcsec with respect to centre of plot
(or annotation for UV-plane plots)
Equatorial coordinates:
DEGREE right ascension and declination in decimal degrees
RADEC right ascension (hhmmss) and declination (ddmmss)
DDEGREE relative right ascension and declination in decimal degrees
w.r.t. centre of plot
DRADEC relative right ascension (hhmmss) and declination (ddmmss)
w.r.t. centre of plot
These annotations will be printed along the left and bottom sides of the plot.
By default, (l,m) pixel-coordinates are shown along the top and right axes side irrespective of what you select. You may suppress these, by prefixing any of the above options with an O for 'Only'.
Example:
ONONE will suppress all annotations.
Prompt: Number of steps for coordinate contouring near pole
Expected input: Integer: 1 value
Specify the number of steps across the map to use in defining the coordinate grid for contouring of coordinates near the pole.
Prompt: Coordinate grid style
Expected input: Character *24: 1 value
Select the style for plotting coordinate grid lines:
TICK give along plot edges only DOTTED dotted grid FULL full-drawn grid
Prompt: data types to plot
Expected input: Character *16: 1 value
Specify the data type(s) to be plotted.
DATA or * plot the data as given in the map
SLOPE plot the horizontal slope of the data (This option is still
experimental)
Prompt: Visibility component to plot
Expected input: Character *16: 1 to 6 values
Specify the visibility component to be plotted.
The quantity plotted depends on the data selected. For TEL or INTERF
and for redund. RES : gain-1(%
ampl (WU), phase(deg For Selfcal RES with external model:
Standard representations of complex data:
Model Resid Int.model
AMPLITUDE
PHASE
COSINE
SINE
AGAIN Re log(data/model) * 100 = gain in %
PGAIN Im log(data/model) * 180/pi = phase in deg
Old WSRT 'PLOTAP' formats:
AP amplitude/phase plots, one pair per page
CS cosine/sine plots, one pair per page
Expected input: Real *16: 1 to 6 values
Prompt: Dotted-contour levels
Expected input: Real: 1 to 32 values
Specify up to 32 values of the contours to be drawn as dotted lines.
Prompt: Full-contour levels
Expected input: Real: 1 to 32 values
Specify up to 32 values of the contours to be drawn as full lines.
Prompt: Halftone transfer function
Expected input: Character *24: 1 value
At this point, data values have been normalised to lie within the interval [0,1]. Halftones are represented by the same interval: 0=white, 1=black. You are now to define the transfer function F for mapping data values onto halftones:
halftone = F (normalised data value)
Continuous functions:
CONTINUE a quadratic function (you will be prompted for the
coefficients)
NONE direct mapping: halftone level = normalised data value
Discontinuous functions:
STEP F is a staircase function; halftone shades are generated by a
stochastic algorithm
PATTERN as STEP, but halftone shades are represented by a set of
fixed patterns
In selecting a method, bear in mind that the human eye is quite sensitive to density variations in light shades while very poorly perceiving the same variations in the dark shades; in other words, its response to density variations is quasi-logarithmic.
To compensate for this, a quasi-exponential transfer function is suitable. The best approximation to this available here is a steeply quadratic function (i.e. specify CONTINUE here and consult the on-line help for the TRANSFORM parameter).
You may judge the quality of your transfer function from the grey-scale wedge that will appear side by side with your plot.
Prompt: Integration time (sec)
Expected input: Real: 1 value
Specify the time interval over which you want to integrate (if possible) before calibrating. The value you specify will be rounded down to a multiple of the hour-angle interval between successive scans.
'*' and '0' mean do not integrate, i.e. calibrate per scan.
The largest value allowed is 3600 (= 1 hour).
Prompt: Special HA plot coordinates
Expected input: Character *10: 1 value
This parameter selects a coordinate conversion for the vertical (HA) plot coordinate in plots of .SCN-file entities.
ST Sidereal time i.s.o. HA. This is useful for plotting a series of
observations (e.g. calibrators-object-calibrators) in a time
sequence, e.g. to survey interference. Vertical coordinate is
ST in degrees
SEQUENCE Pseudo sidereal time: Sidereal time is forced into an ascending
sequence: When the start ST for a sector is less than that of
the one just plotted, it is changed to make the new sector
follow the previous one contiguously. Within each sector,
vertical scale size is that of HA or ST, but the sectors are
displaced in ST. Sectors are plotted in order of their index.
This mode is useful to stuff a lot of information into a single
plot, e.g. to check for interference, but the plot may become
too confusing.
I<xxx> The prefix I indicates that you want to integrate scans; you
will be prompted for the HA interval over which to integrate.
As currently implemented, this mode is effective only for plots
that have HA or (pseudo)ST as vertical coordinate. The plot
scale for this coordinate will not be affected.
NPLOT will set plotting mode according to your reply and return to the OPTION prompt. The mode will remain in force until you change it or NPLOT exits.
Prompt: HA plot scale (degree/cm)
Expected input: Real: 1 value
Specify the hour-angle scale in degree/cm.
Prompt: Select data cross-section
Expected input: Character *16: 1 value
Specify the cross section through the visibility data cube to be plotted:
Consider the interferometers arranged in an upper-triangular matrix:
00 01 02 ... 0B 0C 0D
11 12 ... 1B 1C 1D
22 ... 2B 2C 2D
: : :
BB BC BD
CC CD
DD
Then the possible plotting modes are
visibilities as function of hour angle per interferometer:
NORMAL interferometer order in the matrix is row by row
INVERT interferometer order in the matrix is column by column .
SORT interferometers in order of ascending baseline
other cross sections of the hour-angle/interferometer/channel cube:
SPECTRAL visibilities as function of spectral channel and hour angle,
per interferometer (the WSRT 'PLUVO' format)
BAND visibilities as function of channel and interferometer,
interferometer order as for NORMAL
Prompt: Parameter to plot
Expected input: Character *8: 1 value
Specify action to perform:
Telescope parameters:
TPON total power data (noise source off)
TPOFF total power data (noise source on)
TSYS system temperatures
ISYS system temperatures (X+Y)
GAIN IF gains
Interferometer parameters:
GNCAL gain correction method
TSYSI constant system temperature
TNOISI constant noise source temperature
RGAINI constant receiver gain
Prompt: Type of data to plot|
Expected input: Character *24: 1 value
Specify type of data to plot:
.WMP-file data:
MAP image(s) from .WMP file
.SCN-file visibilities:
DATA observed visibilities
MODEL model visibilities
RESIDUAL visibility residuals (after correction of all known
errors and division by the visibilities of a source
model (yet to be specified)
(sets I=1, QUV=0)
.SCN-file correction parameters:
TELESCOPE telescope phase/gain corrections
INTERFEROMETER interferometer phase/gain corrections (i.e. all
corrections combined per interferometer)
IFDATA IF-data: total powers, system temperatures etc.
Plotting versus sidereal time i.s.o. hour angle:
SPECIAL will prompt for a special mode
QUIT terminate NPLOT
Prompt: Number of plots per page in hor. and vert. directions
Expected input: Integer: 1 to 2 values
Specify number of plots to be plotted on one page.
Prompt: Plot heading (Yes/No) ?
Expected input: Character *24: 1 value
Specify if you want to have a MAP plot with or without the heading.
Prompt: Mark source positions
Expected input: Character *24: 1 value
Specify if you want model-source positions marked in your plot. The answers may be:
NO
YES position markers only
MAMES position markers annotated with their IDs from the model list
The marker symbol used is determined per source by its Type (which is the suffix number in its ID).
EDIT invoke model-handling code to modify model-components' Types,
(FEDIT option), then return to this prompt. This path also
allows you to define additional annotations.
NMODEL HANDLE/EDIT
parameter SOURCES
parameter TEXT
Prompt: Data representation(s)
Expected input: Character *16: 1 to 4 values
Specify the (combination of) data representations:
CONTOUR Contour plot
HALFTONE Halftone plot
* Equivalent to CONTOUR,HALFTONE
RULED Ruled-surface
POLARISATION Pseudo-vectors of linear polarisation. This requires two
input maps, one holding polarisation strengths
sqrt(Q*Q+U*U) and the other position angles atan(U/Q)/2.
Such maps are prepared with
NMAP FIDDLE xxx
Prompt: Polarised-flux limits (W.U.)
Expected input: Real: 1 to 2 values
No polarisation pseudo-vector will be drown if the intensity of linear polarisation is below the lower limit (and therefore mainly noise); above the upper limit it will be truncated to that limit.
Please specify the limits in Westerbork Units.
Prompt: Polarisation pseudo-vector length scale W.U./cm
Expected input: Real: 1 value
Specify the polarisation pseudo-vector length scale in Westerbork Units /cm.
Prompt: Polarisation representation
Expected input: Character *16: 1 value
Specify if polarisation (POL) or magnetic field (MAG) should be plotted
Prompt: Halftone saturation limits
Expected input: Real: 1 to 2 values
Specify the range of values to be covered by the full range of halftone shades.
The first value is the minimum to be represented by 'white', the second value the to be represented by 'black'.
NOTES:
Values outside this range will always be white. (If you think this is a
bad idea, please submit a Bug Report.)
It is not possible to invert the scale by specifying a maximum<minimum.
Prompt: Ruled-surface intensity range (W.U.)
Expected input: Real: 1 to 2 values
Specify the intensity limits in Westerbork Units for the ruled surface plot. Values outside the limits will be truncated.
Prompt: Ruled-surface height scale (W.U./cm)
Expected input: Real: 1 value
Specify the ruled-surface height scale in Westerbork Units /cm.
Prompt: Magnitude scale (W.U./mm or Expected input: Real: 1 value
Specify the magnitude scale:
in Westerbork Units /mm for source/model visibilities and visibility
residuals
in percent/mm for telescope corrections
amplitude noises recorded in the sector headers selected. For other DATA_TYPEs it is a value that is likely to give reasonable output.
Expected input: Real: 1 value
Prompt: Phase scale (W.U./mm or deg/mm)
Expected input: Real: 1 value
Specify the phase scale:
in Westerbork Units /mm for residuals
in degrees/mm for source/model visibilities; for telescope
corrections.
The default is a value that is likely to give reasonable output.
Prompt: Plot scaling factors (horizontal, vertical)
Expected input: Real: 1 to 2 values
At this point, the plot has been dimensioned to fit on a single plotter page or terminal screen, but will not necessarily fill it. You may blow it up in either or both dimensions with the factors you specify here.
If necessary, the blown-up plot will be distributed over more tham one page.
Prompt: Source pair for annotation
Expected input: Character *10: 1 to 2 values
Give the names of two sources that you have selected for plotting. A connecting line will be drawn between them. You will be prompted for an annotation, which defaults to the separation in degrees.
Prompt: Annotation for source pair
Expected input: Character *80: 1 value
The annotation (max 80 characters) for the source pair just selected
Prompt: Grey-scale transfer coefficients:|-
Expected input: Real: 1 to 3 values
Specify the range coefficients for the CONTINUOUS quadratic transfer function that you selected.parameter HALFTONE
Remember that the data at this point have been normalised to the range [0,1]. You may specify 5 values, of which the first three are REQUIRED:
m,M Range of normalised data values to be represented by the full
halftone range. Values outside this range will be truncated.
a,b,c The 0-th through 2nd-order coefficients in the transfer
quadratic.
The result will be ('ndv' = normalised data value):
ndv < m: OUT = 0 (white)
m < ndv < M: OUT = a + b*IN + c*IN*IN (grey scale)
ndv > M: OUT = 1 (black)
You may break the IN range up into partial ranges by specifying multiple sets of m,M,a,b,c separated by semicolons, or specifying the sets one by one as the prompt is repeated. Input will be considered complete when you give no new reply.
Examples:
standard linear, halftone=ndv: 0,1, 0,1
ndv distance from .5: 0,.5, 1,-2; .5,1, -1,2
four grey levels: 0,.25,0; .25,.5,.25; .5,.75,.5; .75,1,1
an approximation to an exp
that seeks to match the
quasi-logarithic response
of the human eye: 0,1, 0,.1,.9
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