Success! Fixing the Dome to Scope Synchronisation Alignment

At last! I had been having problems getting the dome to sync up with the telescope direction in all the sky.

The majority of the sky, approx 80% the telescope could see out of the dome slit, but even for some of this the guide scope was obscured and could not see the sky.

The rest of the time the telescope was partially or fully obstructed by the dome.

I had had enough and went back to basics, read through the manuals, investigated the forums, rechecked the dome centralisation, the shape of the dome was symmetrical and all the offset measurements.

Having checked the dome was central with the floor marking and the previously drilled hole underneath the floor cover, and the distance to each wall post was nearly exactly the same. Then I checked the offsets. This is where I had made my first mistake.

I had been using the wrong reference point on the mount. Originally I had used the central bar of the mount, but I should have been using the axis crossing point of the RA and DEC axis. This impacts the North South offset significantly.

The second mistake was the GEM Offset. This is the point of rotation distance to the centre of the telescope. Originally I had not factored in the guidescope.

Having checked all this and punched in the numbers, took the telescope for a spin round the dome, and all was perfect! IN ALL DIRECTIONS!


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