The Triangulum Galaxy

Now this was an adventure! I’ve long admired many of the starburst galaxy images I’ve seen with continuum subtracted nebulosity data. So I thought I would try the same thing myself with my new ALPT filter. Plus, the extended focal length of the new telescope really enabled me to zoom in on the details of that nebulosity in our nearest neighbor, M33. The downside to this plan was that the fame size of my camera is too small to capture all of this in one frame, so I needed to split this into a mosaic of two panels, and for each panel, I needed to capture enough broadband data and enough narrowband data to make it worthwhile, so I targeted about 8 hours of each for each panel. I made use of some moonlit clear nights to capture the narrowband data and then spent the last few clear moonless nights capturing the broadband data with my triband filter.

Through this process, I’ve learned a few things. 1) I’m still very much a novice when it come to collimating a newtonian telescope. My collimation certainly got worse before it got better, and I tossed lots of frames and spent several more nights than planned on this project because of this. 2) Processing a mosaic is already a challenge with balancing matching color processing, managing differing gradients, and because I planned to do continuum subtraction, I needed to make two two panel mosaics, star align them, and then get to work on subtraction. I really struggled with this using the Gradient Merge Mosaic Process and fortunately found the Photometric Merge Mosaic process, which works much better for me. 3) Even with Franklin Marek’s Continuum Subtraction Tool (The Easy Button!), I found continuum subtraction to be a little more complicated and nuanced of a process. Nonetheless, after many hours, I’ve gotten a result that I’m happy with and ready to share!