Triangulum Galaxy (M33) & Heart Nebula (IC1805)

A couple of nights ago, I re-familiarized myself with my Seestar S50. After a six-month break from any real astrophotography, I found myself fumbling a bit with even this simple but brilliant scope. It took a bit, but I remembered the polar alignment function for EQ mode is buried in the advanced settings menu. This feels like an inconvenient placement decision if you ask me. Let me know if I’m boneheaded and there’s an easier way to access the polar alignment menu.

I turned on the dew heater, let the Seestar reach the ambient temperature, and targeted the Triangulum Galaxy (M33). The first few subframes looked good, so I let it continue shooting and moved on to my Dwarf 3.

For the Dwarf 3, the night’s target was the Heart Nebula (IC 1805). The field of view for the Dwarf 3 is just a bit too tight to get the entire nebula in the frame. I decided to go ahead with a single panel shot rather than a mosaic as I’m not too fond of the Dwarf’s mosaic mode.

The Dwarf 3 employs a more traditional framing approach, where the user selects a specific number of overlapping panels, whereas the Seestar lets the user rotate the frame, adjust the field of view, and then the Seestar uses an algorithm to gradually spiral out, ensuring that the desired total frame is covered by an adequate number of subframes.

I honestly prefer the Dwarf 3’s method as currently the Seestar rejects quite a few subframes, which wastes precious imaging time. However, the Dwarf 3 calculates the adequate number of frames to cover the entire frame for the number of panels selected, and this number cannot be adjusted. This means the user is stuck with the number of subframes the Dwarf selects.

I guess you could use planning mode to plan the mosaic and duplicate the plan to run multiple times in an evening, but I haven’t tried this yet, and it doesn’t seem like a good workflow from a user perspective.

I already had darks which matched the Dwarf’s sensor temperature of 29C, so I was ready to shoot.

The skies were clear, winds were calm, and it was just above freezing. It would have been a perfect night for astrophotography if it weren’t for the insidiously bright moon.

At 88% illuminated and quickly rising, I knew I’d have a ton of light to deal with once I got to the post-processing stage. After 4 hours of shooting on both telescopes, they returned to their home positions and turned off.

Processing:

For these images, I stacked the subframes in Siril and moved them over to PixInsight for processing. I applied BlurXTerminator and NoiseXTerminator at default settings after cropping and color correcting and stretched the image with a standard histogram transformation stretch. Finally, I removed the stars with StarXTerminator and set the star images aside for a moment.

M33:

I extracted a luminance channel of the starless image and opened the LRGB Combination tool. I applied the newly extracted luminance component to the L channel and disabled the R, G, B channels. Then I dragged the saturation slider to .250 under transfer functions, checked the box to apply chrominance noise reduction, and applied the edits to the starless image. This brought out the initial saturation of the blue rim and warm center of the Andromeda galaxy.

From there, I adjusted some final saturation and luminance details with the curves adjustment tool. I wanted to add a bit more structure to the spiral of the galaxy, so I created a light mask with the range selection tool and applied a very light iteration of local histogram equalization of about .15. Finally, I combined the stars and starless images in Pixel Math using the formula ~(~Starless*~Stars) and exported the image.

Heart Nebula:

I first tried to use the narrowband normalization tool in PixInsight, but this resulted in some weird color palettes. So I went back to an older method and extracted the R, B, G, channels of the one-shot color image. I deleted the initial blue channel and then recreated this channel by combining the red and green channels in Pixel Math using the formula R*.6 + G*.4. I recombined the color channels in the LRGB combination tool using red for both the luminance and red channels, and flipped the blue and green channels in the tool. Then I dragged the saturation slider to .250 under transfer functions, checked the box to apply chrominance noise reduction, and applied the edits to the starless image.

From here I made final curve adjustments and recombined the starless image and stars using the same process as M33. I’d say both images turned out pretty well based on the short amount of integration time on the targets.