I’ve imaged M33 before but this image takes it to another level. It also took processing to another level of complexity.
The combination of this telescope and camera provide an image scale of 0.8 arcseconds/pixel which is quite good. it’s twice as fine as the 1.6 arcseconds/pixel that I achieved with my 80mm telescope. That should allow quite a bit more detail to be resolved. However, M33 was too large to fit into the field of view of the camera. The solution was a two panel mosaic. This gets the wide field of view needed and the fine resolution but doubles the amount of data to be collected and requires extra work to assemble the mosaic before normal processing can begin.
The result was a total of 95.5 hours of data acquisition. This is by far the most I’ve devoted to any one project but the data was quite clean and although I had a couple of false starts and one hiccough to deal with when assembling the mosaic it was a fairly straightforward if somewhat tedious process. Except for the last step of actually creating the assembled mosaic panels it was fairly mechanical.
Once I had the mosaic assembled it was on to normal processing. I’ve found that I have a tendency to push data too hard, especially galaxies. I’m not sure why, but I wanted to avoid that in the image. Galaxies shouldn’t have hard edges and I wanted this image to have soft edges while still allowing the detail in the center to shine. I knew the data would support this. The only question is whether I could accomplish it. I also wanted to color to be noticeable but not too intense. I’d have liked a bit more color but if I pushed harder to began to look artificial. I also tried to optimize the image for viewing the entire image and not necessarily for pixel peeping although I think it holds up reasonably well.
You can find all the technical details at astrobin.
For comparison, here’s the previous attempt: