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AlignOffset - Align SkyFrames using the offset coordinate system?

Description:
This attribute is a boolean value which controls how a SkyFrame behaves when it is used (by astFindFrame or astConvert) as a template to match another (target) SkyFrame. It determines the coordinate system in which the two SkyFrames are aligned if a match occurs.

If the template and target SkyFrames both have defined offset coordinate systems (i.e. the SkyRefIs attribute is set to either "Origin" or " Pole"), and they both have a non-zero value for AlignOffset, then alignment occurs within the offset coordinate systems (that is, a UnitMap will always be used to align the two SkyFrames). If either the template or target SkyFrame has zero (the default value) for AlignOffset, or if either SkyFrame has SkyRefIs set to "Ignored", then alignment occurring within the coordinate system specified by the AlignSystem attribute.

Type:
Integer (boolean).
Class Applicability:
SkyFrame
All SkyFrames have this attribute.


next up previous 264
Next: AlignSideBand - Should the SideBand attribute be taken into account when aligning this DSBSpecFrame with another DSBSpecFrame?
Up: AST Attribute Descriptions
Previous: Adaptive - Should the area adapt to changes in the coordinate system?

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