The Witches Broom (NGC 6960) - a classic and one of my favorite targets in the night sky. The red Hydrogen Alpha laced with the blue-green Oxygen III ripple outwards from the center of a supernova that occurred 5,000-8,000 years ago about 1,500 light years from Earth -
How Do We Know It: Supernova Remnant Age | NASA Blueshift. This image is a tighter crop on the Witches Broom, within the larger
Veil Nebula - Cygnus Loop ( Scott Hall ) - AstroBin, using a reduced Stellarvue SVX102T telescope in combination with the Player One Uranus-C Pro camera and Antlia ALP-T filter. Mouse over the image above for a starless version.
This project started off as a test image for the SVX102T back spacing and the Uranus-C Pro camera matched with the ALP-T filter to see what I could do with a dual narrow band filter and a color camera from a Bortle 7 light polluted region. As you can imagine I was pleasantly surprised with the result. I tried extracting the Ha and OIII in proportions that compensated for the overlapping Bayer matrix on the camera but in the end, I decided to ditch that processing path because the results simply looked too rough. I probably will reserve the one-shot color camera for brighter targets like this one and comets in the future. Monochrome imaging, I think, produces the best results for most other deep sky targets.
A couple firsts for me on this project: 1. Stellarvue SVX102T with the reducer dialed in for back spacing - fairly easy to do with a smaller sensor.
2. Player One Uranus-C Pro camera - performed well, although I had an issue with the USB-C connector on the camera that Player One fixed in rapid fashion.
3. Antlia ALP-T dual narrow band filter - Performed well in my Bortle 7 light pollution although I mostly used it without the Moon.
4. Dual Narrow band filter processing - Trial and error showed that the best processing path turned out the be the easiest path in my case where I processed the one shot color camera straight up without trying to extract the Ha and OIII signal separately and recombine as an HOO image.
5. GraXpert Artificial Intelligence gradient removal with the PixInsight script - this worked awesome and with just a touch of smoothing it took care of the gradients in short order.
6. StarNet 2 - StarXTerminator was pulling out too much of the non-stellar data into the stars only data no matter what options I tried. In the end I gave StarNet 2 a shot and it just worked with minimal artifacts.
A MysterySee this star in the center of the clip below? It's the only one in the entire field that appears with star spikes in my subframes and the stacked image. The star is a Long-Period Variable, possibly an eclipsing binary with a white dwarf, and more information is available from the CDS Portal here:
CDS Portal (u-strasbg.fr). The spikes show up prominently in the infrared images on the portal although I wouldn't expect infrared to make it through the ALP-T filter. I doubt it's the filter or the camera causing this effect because its unique to this star in the field of 7336 stars.
Any thoughts on what is going on here?
Processing performed in PixInsight using the following steps: 1. GraXPert AI
2. SPCC
3. BlurXTerminator
4. StarNet2
5. Stars Processing
1. ArcsinhStretch
2. HistogramTransformation
3. NoiseXTerminator
4. Curves Increase Saturation
5. Invert
6. Bill Blanshan Modified SCNR v5
7. Invert
8. Bill Blanshan Modified SCNR v5
6. Starless Processing
1. NoiseXTerminator
2. GeneralizedHyperbolicStretch
3. Curves
7. Stars Starless Combine
8. Bill Blanshan StarReductionMethod3 1x Soft reduction
9. Resample
10. DynamicCrop
11. Save as JPG
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