[PRejto (Peter)]

Well, a bug got planted in my head by a certain well known imager here. Not sure if he was joking or not(!!),but I posted a picture of my MEII with a TEC140 mounted to the rings of my new TEC180. This certain "firebrand" suggested that I ought to capture luminance with one scope and colour with the other. Now, of course, I have enough trouble running one scope but running two simultaneously seems like a big ask. But, the idea is festering as they do and I'm looking for a good excuse to hold onto the TEC140. So.....

A few calculations.

TEC180 with G2-8300 CCD = .88 arc-sec FOV ~ 37x49 arc-min
TEC180 with Trius = .74 arc-sec FOV ~ 27x34 arc-min
TEC180 Theoretical resolution = .66 arc-sec

TEC140 with G2-8300 = 1.14 arc-sec FOV ~ 48x63 arc-min
TEC140 with Trius = .95 arc-sec FOV ~ 35x43 arc-min
TEC140 Theoretical resolution = .8 arc-sec

It would seem that the TEC180/G2-8300 and TEC140/Trius combination give a very close match in FOV and resolution. I think my inclination would be to run the TEC140/Trius for colour and the TEC180/G2-8300 for luminance. My reasoning would be that the Trius sensitivity might grab the colour more easily, and the TEC180 (and higher resolution) would be good for luminance. Hopefully the increased aperture but less sensitive camera would work well. On the other hand, it also comes to mind that not matching the FOV could provide for a nice wide-field view from the TEC140 (colour) and luminance data on the object of interest. I'm just not sure at all about the technique of combining stacks that are at differing resolutions. I know that CCDStack will combine 1x1 with 2x2. Will it also do intermediate values?

The next issue would be whether there is any hope of accurate guiding of both scopes with one piggybacked on top of the other. Is it worth trying, or is it a hopeless combination in terms of flexure? Would side by side mounting be better or also problematic? I also imagine getting both scopes pointing exactly so the target is centred in both to be difficult. Would this be done with shims?

Then there would be issues re running two focusers, two cameras, etc etc.

Hopeless? Insanity? I'm intrigued by anything that might take greater advantage of the limited nights of good seeing in Sydney!

I'd appreciate some input here as I'm off to the USA for 2 weeks. If I need certain gear to pull this off I could bring it back with me hopefully. I'm bringing my TEC Focuser off the 180 to have a custom motor fitted at Starizona, and while I'm gone a machine shop is drilling out my MX weights so they will fit on the MEII shaft.

Thanks,

Peter