Rotator.PABias Property

Rotator.PABias (read-only, Double)

The difference (degrees) between the mechanical rotator angle and the sky PA

Syntax

Rotator.PABias

The property syntax has these parts:

Part	Description
Value (Double)	The difference (degrees) between the mechanical rotator angle and the sky PA

Remarks

This value is maintained in the registry by ACP observing logic (AcquireSupport) and is updatged at each plate solution. Thus, it is dynamic, and may be used to detect problems in the rotator (changing PABias indicates slippage, cogging, encoder problems, etc.).

The sign of this number is such that the sky PA can be calculated as shown:

SkyPA = Rotator.Position - Rotator.PABias;    // Note sign for conversion
If Util.GEMWestOfPier Then  SkyPA += 180.0;   // If GEM looking west, roll it over
SkyPA = RangeAngle(SkyPA, 0.0, 360.0);        // Range the PA 0-360

Will raise an error if no rotator is connected.