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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.


next up previous 264
Next: AST_FORMAT - Format a coordinate value for a Frame axis
Up: AST Routine Descriptions
Previous: AST_FITSTABLE - Create a FitsTable

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 210
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2009 Science \& Technology Facilities Council