When training Periodic Error Correction on a Paramount using the Bisque TSC – Periodic Error Correction – Compute PEC Curve tab, the West check box can be confusing.

For the West box if your mount is pointing East with the camera at 0° position angle (PA) and you flip the mount (with no rotation of the image train) to collect data West of the meridian the camera is now at 180° PA (upside down).  In this case you would check the West box when you save the fit data to the mount.

If you’re on the West side but the camera is at 0° PA (not upside down) you would not check the West box.

Basically 0° camera PA no West check box

180° camera PA check the West box, regardless of pier side.

The exception to this is if your system produces a mirror image, this is why checking camera PA with image link is important, it tells you if the image is mirrored or not.  If mirrored you basically reverse the above.

If you find the PEC has doubled the box is most likely the problem.  In this case you would just do the opposite and re save the log and grab another correction log to confirm.

Notes: for a raw PE tracking log the West box does not matter, only when you save to mount as the box is telling the control system if the curve is inverted or not.

Camera position angle is very important when collecting data for the PE curve, the camera must be at an angle of either 0° or 180° give or take a degree or so.

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