AMPRATIO( ) = _REAL (Read)
If number of beam positions given by BEAMS is more than one,
this specifies the ratio of the amplitude of the secondary
beams to the primary. Thus you should supply one fewer value
than the number of beams. If you give fewer than that the last
ratio is copied to the missing values. The ratios would
normally be negative, usually
. AMPRATIO is ignored
when there is only one beam feature to fit. [!]
BEAMS = _INTEGER (Read)
The number of beam positions to fit. This will normally be
1, unless a chopped observation is supplied, when there may
be two or three beam positions. This parameter is ignored
for "File" and "Catalogue" modes, where the
number comes from the number of beam positions read from the
files; and for "Interface" mode when the beam positions POS,
POS2, etc. are supplied in full on the command line
without BEAMS. In all modes there is a maximum of five
positions, which for "File" or "Catalogue" modes
will be the first five. 
COIN = FILENAME (Read)
Name of a text file containing the initial guesses at the
co-ordinates of beams to be fitted. It is only accessed if
Parameter MODE is given the value "File". Each line should
contain the formatted axis values for a single position, in the
current Frame of the NDF. Axis values
can be separated by spaces, tabs or commas. The file may
contain comment lines with the first character # or !.
DESCRIBE = LOGICAL (Read)
If TRUE, a detailed description of the co-ordinate Frame in
which the beam positions will be reported is displayed before
the positions themselves. [current value]
DEVICE = DEVICE (Read)
The graphics device which is to be used to give the initial
guesses at the beam positions. Only accessed if parameter
MODE is given the value "Cursor".
[Current graphics device]
FIXAMP = _DOUBLE (Read)
This specifies the fixed amplitude of the first beam.
Secondary sources arising from chopped data use FIXAMP
multiplied by the AMPRATIO. A null value indicates that
the amplitude should be fitted. [!]
FITAREA() = _INTEGER (Read)
Size in pixels of the fitting area to be used. This should
fully encompass the beam and also include some background signal.
If only a single value is given, then it will be duplicated to all
dimensions so that a square region is fitted. Each value must
be at least 9. A null value requests that the full data
array is used. [!]
FIXBACK = _DOUBLE (Read)
If a non-null value is supplied then the model fit will use
that value as the constant background level otherwise the
background is a free parameter of the fit. [!]
FIXFWHM = LITERAL (Read)
If a non-null value is supplied then the model fit will use
that value as the full-width half-maximum value for the beam
and assumes that the beam is circular. If two values are
supplied then these are the fixed major- and minor-axis
full-width half maxima.
If the current co-ordinate Frame of the NDF is a SKY Frame
(e.g. right ascension and declination), then the value should
be supplied as an increment of celestial latitude (e.g.
declination). Thus, "5.7" means 5.7 arcseconds, "20:0" would mean 20 arcminutes, and "1:0:0" would
mean 1 degree. If the current co-ordinate Frame is not a SKY
Frame, then the widths should be specified as an increment
along Axis 1 of the current co-ordinate Frame. Thus, if the
Current Frame is PIXEL, the value should be given simply as a
number of pixels.
Null indicates that the FWHM values are free parameters of the
FIXPOS = _LOGICAL (Read)
If TRUE, the supplied position of each beam is used and
the centre co-ordinates of the beam features are not fit.
FALSE causes the initial estimate of the location of each
beam to come from the source selected by Parameter MODE, and
all these locations are part of the fitting process (however
note the exception when FIXSEP=TRUE. It is advisable not to
use this option in the inaccurate "Cursor" mode. [FALSE]
FIXSEP = _LOGICAL (Read)
If TRUE, the separations of secondary beams from the primary
beam are fixed, and this takes precedence over parameter
FIXPOS. If FALSE, the beam separations are free to be fitted
(although it is actually the centres being fit).
It is advisable not to use this option in the inaccurate
"Cursor" mode. [FALSE]
GAUSS = _LOGICAL (Read)
If TRUE, the shape exponent is fixed to be 2; in other words
the beams are modelled as two-dimensional normal distributions.
If FALSE, the shape exponent is a free parameter in each fit.
INCAT = FILENAME (Read)
A catalogue containing a positions list giving the initial
guesses at the beam positions, such as produced by applications
CURSOR, LISTMAKE, etc. It is only accessed if Parameter MODE
is given the value "Catalogue".
LOGFILE = FILENAME (Read)
Name of the text file to log the results. If null, there
will be no logging. Note this is intended for the human reader
and is not intended for passing to other applications. [!]
MARK = LITERAL (Read)
Only accessed if Parameter MODE is given the value "Cursor".
It indicates which positions are to be marked on the screen
using the marker type given by Parameter MARKER. It can take
any of the following values.
- "Initial" -- The position of the cursor when the mouse
button is pressed is marked.
- "Fit" -- The corresponding fit position is marked.
- "Ellipse" -- As "Fit" but it also plots an ellipse at the
HWHM radii and orientation.
- "None" -- No positions are marked.
MARKER = INTEGER (Read)
This parameter is only accessed if Parameter MARK is set TRUE.
It specifies the type of marker with which each cursor
position should be marked, and should be given as an integer
PGPLOT marker type. For instance, 0 gives a box, 1 gives a
dot, 2 gives a cross, 3 gives an asterisk, 7 gives a triangle.
The value must be larger than or equal to
. [current value]
MODE = LITERAL (Read)
The mode in which the initial co-ordinates are to be obtained.
The supplied string can be one of the following values.
- "Interface" -- positions are obtained usingparameters POS,
- "Cursor" -- positions are obtained using the graphics cursor
of the device specified by Parameter DEVICE.
- "Catalogue" -- positions are obtained from a positions list
using Parameter INCAT.
- "File" -- positions are obtained from a text file using
NDF = NDF (Read)
The NDF structure containing the data array to be analysed. In
cursor mode (see Parameter MODE), the run-time default is the
displayed data, as recorded in the graphics database. In other
modes, there is no run-time default and the user must supply a
PLOTSTYLE = GROUP (Read)
A group of attribute settings describing the style to use when
drawing the graphics markers specified by Parameter MARK.
A comma-separated list of strings should be given in which each
string is either an attribute setting, or the name of a text
file preceded by an up-arrow character "
". Such text files
should contain further comma-separated lists which will be
read and interpreted in the same manner. Attribute settings
are applied in the order in which they occur within the list,
with later settings overriding any earlier settings given for
the same attribute.
Each individual attribute setting should be of the form:
is the name of a plotting attribute, and
is the value to assign to the attribute. Default values will be
used for any unspecified attributes. All attributes will be
defaulted if a null value (!)--the initial default--is supplied.
To apply changes of style to only the current invocation, begin these
attributes with a plus sign. A mixture of persistent and temporary
style changes is achieved by listing all the persistent attributes
followed by a plus sign then the list of temporary attributes.
See Plotting Attributes
for a description of the available attributes. Any unrecognised
attributes are ignored (no error is reported). [current value]
POLAR = _LOGICAL (Read)
If TRUE, the co-ordinates supplied through POS2-POS5 are
interpreted in polar co-ordinates (offset, position angle)
about the primary beam. The radial co-ordinate is a distance
measured in units of the latitude axis if the
current WCS Frame
is a SKY DOMAIN or the first axis for other Frames. For a
SKY current WCS Frame, position angle follows the standard
convention of North through East. For other Frames the angle
is measured from the second axis anticlockwise, e.g. for a
PIXEL Frame it would be from y through negative x, not the
standard x through y.
If FALSE, the co-ordinates are the regular axis co-ordinates
in the current Frame.
POLAR is only accessed when there is more than one beam to fit.
POS = LITERAL (Read)
When MODE = "Interface" POS specifies the co-ordinates
of the primary beam position. This is either merely an
initial guess for the fit, or if Parameter FIXPOS is TRUE, it defines a fixed location. It is specified in the
current co-ordinate Frame of the NDF (supplying a colon ":" will display details of the current co-ordinate Frame).
A position should be supplied as a list of formatted
WCS axis values separated by spaces or commas, and should
lie within the bounds of the NDF.
If the initial co-ordinates are supplied on the command line
without BEAMS the number of contiguous POS, POS2,...
parameters specifies the number of beams to be fit. If the
initial co-ordinates are supplied on the command line without
BEAMS specified only one beam will be fit.
POS2-POS5 = LITERAL (Read)
When MODE = "Interface" these parameters specify the
co-ordinates of the secondary beam positions. These should
lie within the bounds of the NDF. For each parameter the
supplied location may be merely an initial guess for the fit,
or if Parameter FIXPOS is TRUE, it defines a fixed
location, unless Parameter FIXSEP is TRUE, whereupon it
defines a fixed separation from the primary beam.
For POLAR = FALSE each distance should be given as a single
literal string containing a space- or comma-separated list of
formatted axis values measured in the current co-ordinate Frame
of the NDF. The allowed formats depends on the class of the
current Frame. Supplying a single colon ":" will display
details of the current Frame, together with an indication of
the format required for each axis value, and a new parameter
value is then obtained.
If Parameter POLAR is TRUE, POS2-POS5 may be given as an
offset followed by a position angle. See Parameter POLAR for
more details of the sense of the angle and the offset
The parameter name increments by 1 for each subsequent beam
feature. Thus POS2 applies to the first secondary beam
(second position in all), POS3 is for the second secondary
beam, and so on. As the total number of parameters required is
one fewer than the value of Parameter BEAMS, POS2-POS5 are
only accessed when BEAMS exceeds 1.
REFPOS = LITERAL (Read)
The reference position. This is often the desired position for
the beam. The offset of the primary beam with respect to this
point is reported and stored in Parameter REFOFF. It is only
accessed if the current WCS Frame in the NDF is not a SKY
Domain containing a reference position.
The co-ordinates are specified in the current WCS Frame of the
NDF (supplying a colon ":" will display details of the current
co-ordinate Frame). A position should be supplied either as a
list of formatted WCS axis values separated by spaces or
commas. A null value (!) requests that the centre of the
supplied map is deemed to be the reference position.
RESID = NDF (Write)
The map of the residuals (data minus model) of the fit. It inherits
the properties of the input NDF, except that its data type is
_DOUBLE or _REAL depending on the precision demanded by the
type of IN, and no variance is propagated. A null (!) value
requests that no residual map be created. [!]
TITLE = LITERAL (Read)
The title for the NDF to contain the residuals of the fit.
If null (!) is entered the NDF will not contain a title.
["KAPPA - BEAMFIT"]
VARIANCE = _LOGICAL (Read)
If TRUE, then any VARIANCE component present within the input
NDF will be used to weight the fit; the weight used for each
data value is the reciprocal of the variance. If set to FALSE
or there is no VARIANCE present, all points will be given equal