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astRead - Read an Object from a Channel

Description:
This function reads the next Object from a Channel and returns a pointer to the new Object.
Synopsis:
AstObject $*$astRead( AstChannel $*$this )
Parameters:
this
Pointer to the Channel.
Class Applicability:
FitsChan
All successful use of astRead on a FitsChan is destructive, so that FITS header cards are consumed in the process of reading an Object, and are removed from the FitsChan (this deletion can be prevented for specific cards by calling the FitsChan astRetainFits function). An unsuccessful call of astRead (for instance, caused by the FitsChan not containing the necessary FITS headers cards needed to create an Object) results in the contents of the FitsChan being left unchanged.
StcsChan
The AST Object returned by a successful use of astRead on an StcsChan, will be either a Region or a KeyMap, depending on the values of the StcsArea, StcsCoords and StcsProps attributes. See the documentation for these attributes for further information.
Returned Value:
astRead()
A pointer to the new Object. The class to which this will belong is determined by the input data, so is not known in advance.
Notes:
  • A null Object pointer (AST__NULL) will be returned, without error, if the Channel contains no further Objects to be read.

  • A null Object pointer will also be returned if this function is invoked with the AST error status set, or if it should fail for any reason.


next up previous 264
Next: astRebinX - Rebin a region of a data grid
Up: AST Function Descriptions
Previous: astRateMap - Create a RateMap

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2009 Science \& Technology Facilities Council