Frankenscope and NGC1365 - the Great Barred Galaxy

Finally, an image!

I've finally got around to processing an image of NGC1365 - the Great Barred Galaxy - that I got from the ASV's dark sky site in Central Victoria a couple of weekends ago. It isn't the best image I've taken, but it's interesting, and it's my first serious image since before the pandemic!

But it was a challenge - I made things hard for myself by using two scopes, two cameras and one very rusty astrophotographer. 


The colour information in the image was gathered in 51 five-minute exposures using a colour camera on a Sidereal Trading modified telescope. This is one crazy machine. 

The front half - the objective - of the scope is a saxon 102mm FCD100 triplet, which is a beautiful piece of glass. We removed the somewhat unworthy focuser and replaced it with an Astroworx Crayford focuser made in our own factory. This focuser will soon be launched onto the market, and we hope it will do well. The guide scope was made by Sky-Watcher, the guide camera is a QHY, the focus motor is a Pegasus FocusCube, the colour camera is a ZWO ASI071MC-P and the whole arrangement is lifted by an iOptron CEM40ED mount. We've dubbed the rig "Frankenscope" because of the number of contributing brands.

Here's a photo while testing Frankenscope on my neighbour's roof (Photo: Rob Gregory).

The monochrome information for the galaxy image was 20 five-minute exposures in Hydrogen alpha and 27 five-minute exposures in Luminance using my own SharpStar 107mm FPL53 triplet and a ZWO ASI1600MM-P.

Rusty skills

An additional challenge was the technician I had to work with: me. I didn't calibrate the autoguide program on the colour camera, meaning when the stars began to drift, the computer had quite the wrong idea as to how to compensate. When the mount wavered during the first exposure, the mount compensated the wrong way, and got utterly lost. I re-calibrated, but didn't re-centre the image, so the galaxy ended up on one side of the frame rather than the middle. I was wanting some of the nearby Fornax galaxy cluster but because of all this, I only got a couple. 

Putting it all together

Processing these sets of sub-images, along with their calibration frames into five stacks was difficult but once I got the workflow right (thanks to the helpful people at Astro Pixel Processor) it was pretty straightforward. Half of the red information you see on your computer screen comes from the red from the colour camera, and the other half of the red is the Hydrogen alpha from the monochrome camera. Blue is just from the colour camera, as is green, although I had to tone the green down a little. The luminance information sits over the top of all this.

The image is fairly heavily cropped due to the framing problems I had.

I like the addition of Hydrogen alpha into the red channel. It emphasises the little knotty nebulas in the arms of the galaxy (which are hard to spot in the zoomed-out view). I left the image pretty noisy as I didn't want to erase little galaxies in the background - and there are lots. Here's a slightly zoomed-in view. I count three tiny galaxies in this crop alone.

But did I enjoy it?

Overall, working with two scopes simultaneously is difficult. Not only the processing, but the data gathering is a real juggling act, and I made lots of mistakes. Part of the enjoyment of astrophotography is the quiet, almost meditative atmosphere at the scope while it does its thing. 

Instead of this, I was running around like a chook without a head.

Next time, I think I'll stick to one scope at a time.