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GrismEps - The angle between the normal and the dispersion plane

Description:
This attribute holds the angle (in radians) between the normal to the grating or exit prism face, and the dispersion plane. The dispersion plane is the plane spanned by the incoming and outgoing ray. The default value is 0.0.
Type:
Double precision.
Class Applicability:
GrismMap
All GrismMaps have this attribute.


next up previous 264
Next: GrismG - The grating ruling density
Up: AST Attribute Descriptions
Previous: GrismAlpha - The angle of incidence of the incoming light on the grating surface

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