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A Library for Handling
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AST_FLUXFRAME
Create a FluxFrame
Description:
This function creates a new
FluxFrame
and optionally initialises its attributes.
A FluxFrame is a specialised form of one-dimensional Frame which represents various systems
used to represent the signal level in an observation. The particular coordinate system to
be used is specified by setting the FluxFrame’
s System attribute qualified, as necessary,
by other attributes such as the units, etc (see the description of the System attribute for
details).
All flux values are assumed to be measured at the same frequency or wavelength (as given by the
SpecVal attribute). Thus this class is more appropriate for use with images rather than
spectra.
Invocation
RESULT = AST_FLUXFRAME( SPECVAL, SPECFRM, OPTIONS, STATUS )
Arguments
SPECVAL = DOUBLE PRECISION (Given)
The spectral value to which the flux
values refer, given in the spectral coordinate system specified by SPECFRM. The value
supplied for the SPECVAL parameter becomes the default value for the SpecVal attribute. A
value of AST__BAD may be supplied if the spectral position is unknown, but this may
result in it not being possible for the
AST_CONVERT function to determine a
Mapping
between the new FluxFrame and some other FluxFrame.
SPECFRM = INTEGER (Given)
A
pointer to a
SpecFrame describing the spectral coordinate system in which the SPECVAL
parameter is given. A deep copy of this object is taken, so any subsequent changes to the
SpecFrame using the supplied pointer will have no effect on the new FluxFrame. AST__NULL
can be supplied if AST__BAD is supplied for SPECVAL.
OPTIONS = CHARACTER
(
)
(Given)
A character string containing an optional comma-separated list of attribute assignments to be
used for initialising the new FluxFrame. The syntax used is identical to that for the
AST_SET routine.
If no initialisation is required, a blank value may be supplied.
STATUS = INTEGER (Given and
Returned)
The global status.
Returned Value
AST_FLUXFRAME = INTEGER
A pointer to the
new FluxFrame.
Notes:
-
When conversion between two FluxFrames is requested (as when supplying FluxFrames
AST_CONVERT), account will be taken of the nature of the flux coordinate systems they represent,
together with any qualifying attribute values, including the AlignSystem attribute. The results will
therefore fully reflect the relationship between positions measured in the two systems. In
addition, any difference in the Unit attributes of the two systems will also be taken into
account.
-
A null Object pointer (AST__NULL) will be returned if this function is invoked with STATUS set to an
error value, or if it should fail for any reason.
Copyright (C) 2021 East Asian Observatory
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A Library for Handling
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Systems
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