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StcsCoords
-
Return the Coordinates component when reading an STC-S document?
- Description:
- This is a boolean attribute which controls what is returned
by the
AST_READ
function when it is used to read from an StcsChan.
If StcsCoords is set non-zero, then a PointList
representing the STC Coordinates will be returned by
AST_READ.
If StcsCoords is set to zero (the default), then the STC
Coordinates will not be returned.
- Type:
- Integer (boolean).
- Class Applicability:
-
StcsChan
-
All StcsChans have this attribute.
- Notes:
- Other attributes such as StcsArea and StcsProps can be used to
specify other Objects to be returned by
AST_READ.
If more than one of these attributes is set non-zero, then the
actual Object returned by
AST_READ
will be a KeyMap, containing the requested Objects. In this
case, the PointList representing the STC Coordinates will be
stored in the returned KeyMap using the key "COORDS". If StcsCoords
is the only attribute to be set non-zero, then the Object returned by
AST_READ
will be the Coordinates PointList itself.
- The Coordinates component is specified by the additional axis
values embedded within the body of each STC-S sub-phrase that
represents an extended area. Sub-phrases that represent a single
value ( that is, have identifiers "Time", "Position", "Spectral"
or "Redshift" ) are not considered to be be part of the STC
Coordinates component.
- If the STC-S documents does not contain a Coordinates component,
then a NULL object pointer
(AST__NULL)
will be returned by
AST_READ
if the Coordinates component is the only object being returned. If
other objects are also being returned (see attributes StcsProps and
StcsArea), then the returned KeyMap will contain a "COORDS" key
only if the Coordinates component is read succesfully.
- The TimeFrame used to represent a time STC-S sub-phrase will have
its TimeOrigin attribute set to the sub-phrase start time. If no
start time is specified by the sub-phrase, then the stop time will be
used instead. If no stop time is specified by the sub-phrase, then
the single time value specified in the sub-phrase will be used
instead. Subsequently clearing the TimeOrigin attribute (or setting
its value to zero) will cause the TimeFrame to reprsent absolute times.
- The Epoch attribute for the returned Region is set in the same
way as the TimeOrigin attribute (see above).
Next: StcsLength - Controls output line length
Up: AST Attribute Descriptions
Previous: StcsArea - Return the CoordinateArea component when reading an STC-S document?
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