My mosaic plan is backwards... could it be because I'm using an ONAG?

I have a reflector with an ONAG in my imaging rig. The ONAG is essentially a diagonal that allows IR light to pass through to my guide camera, allowing full frame guiding and focus.

The use of a diagonal means after processing images, I have to do a flip of the image (not rotate, but flip) to get it oriented correctly.

I recently started working on mosaic plans in Telescopius. The one I acted upon first was a two-panel mosaic for the Rosette. I set the mosaic, made sure I had the position angle correct, and copied the RA and DEC coordinates for both panels. I use TheSkyX and directed the scope to go to the Panel 1 coordinates. The results was what was supposed to be Panel 2. I then slew to the Panel 2 coordinates and the resulting image was in the opposite direction, instead of perhaps being what Panel 1 was supposed to be.

So, somehow, the mosaic plan is backwards. I wonder if, because of my ONAG, I am getting things backwards. I had figured coordinates are coordinates, and regardless of how the ONAG orients my image, that I’d at least have two panels that resulted in the expected mosaic panels, even if it was backwards.

Panel 1 was supposed to be (o which is the ‘left’ side of the Rosette
Panel 2 was supposed to be o) which is the ‘right’ side of the Rosette
Panel 1 ended up being o) in the image, which was what Panel 2 was supposed to be!
Panel 2 ended up being ) which was the edge of what I got for Panel 1.

To make sense of the above, from the Panel 2 coordinates, I had to go in the opposite direction of Panel 1 to get the other half of the Rosette.

Any insight?



Hi Billy, welcome to the forum!

You are right, coordinates are coordinates. I’m not sure how you only got the edge of what Panel 1 was supposed to be instead of the whole panel. This is the first report of this kind after years of the mosaic planner being around.

When you say you had to go to the opposite direction, did you move the telescope by hand instead of a goto? Is it possible you got the RA backwards due to the diagonal?