#### Description:

This attribute gives the angle of incidence of light of the reference wavelength (given by attribute GrismWaveR) onto the detector. Specifically, it holds the angle (in radians) between the normal to the detector plane and an incident ray at the reference wavelength. The default value is 0.0.

Note, the value of this attribute may changed only if the GrismMap has no more than one reference. That is, an error is reported if the GrismMap has been cloned, either by including it within another object such as a CmpMap or FrameSet or by calling the astClone function.

Type:

  Double precision.

#### Applicability

##### GrismMap

All GrismMaps have this attribute.
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