NGC2237 Rosette Nebula in HOO

Bootlegger

59853

Deep Sky

Apr 17th, 2022

2452

NGC 2244NGC 2237NGC 2238NGC 2239NGC 2246NGC 2252

Resolution:: 6063x4050 px
File size:: 4700 KB

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Photo description / processing

Cloudy weather, so I reprocessed the Rosette Nebula using esoteric formulas to extract oxygen. Thanks to the Siril team for Pixel Math in the new version—it was sorely missed. The formulas themselves, in a foreign language, are here: https://thecoldestnights.com/2020/06/pixinsight-dynamic-narrowband-combinations-with-pixelmath/

Technical information

Telescope/Lens: Newtonian 150/750
Camera: RisingCam 571C
Mount: Sky-Watcher HEQ5 Pro (belt-modified)
Guide Scope: Pentax Takumar 200mm f/4 Lens
Guide Camera: T7M
Accessories: Sharpstar 0.95x Coma Corrector
Software: Astro Photography Tool (APT), PHD2, Siril, Topaz DeNoise AI, StarNet++, Luminar

Location: Краснознаменск, Россия

Light pollution

Orange, Bortle 6 zone

Date taken: Feb 14th, 2022

Exposure

100 × 120″ · ISO/Gain: 100 · Optolong l-eXtreme · Feb 14th, 2022

Total exposure: 3 h 20 m

Photo versions

Current photoUpdated

NGC2237 Rosette Nebula in HOO

Apr 17th, 2022

3 h 20 m

NGC2237 Rosette Nebula in HOO

Feb 16th, 2022

3 h 0 m

Hooray! The first night suitable for shooting since the beginning of December. Never mind that it was a full moon and I was shooting about 20 degrees from the Moon. The raw frames were scary to look at, but after some gradient work in HOO, it came together nicely. And yes, Starnet++ version 2 is absolutely brilliant—everyone should download it immediately!

Show changes

Comments

Bender B. Rodriguez

NGC2237 Rosette Nebula in HOOfrom 02/16/2022

Very nice!
But the full size could be slightly reduced—to match the image resolution with the level of detail.

Feb 16th, 2022

BootleggerReply to Bender B. Rodriguez

NGC2237 Rosette Nebula in HOOfrom 02/16/2022

My system has a resolution of about 1" per pixel, which is roughly normal sampling. What benefit would there be from resampling the image?

Feb 17th, 2022

Bender B. RodriguezReply to Bootlegger

NGC2237 Rosette Nebula in HOOfrom 02/16/2022

Not compression, but a reduction in pixel size.

Feb 17th, 2022

Bender B. RodriguezReply to Bootlegger

NGC2237 Rosette Nebula in HOOfrom 02/16/2022

Very roughly speaking, if the minimum size of visually significant details is 3 pixels, then the image can be reduced by a factor of 3 without losing the perception of those details. In doing so, all single-pixel noise will disappear, and contrast will form naturally.

Feb 17th, 2022

BootleggerReply to Bender B. Rodriguez

NGC2237 Rosette Nebula in HOOfrom 02/16/2022

This is essentially performing 2x2 or 3x3 binning in software. You can experiment with it.

Feb 17th, 2022

Bender B. RodriguezReply to Bootlegger

NGC2237 Rosette Nebula in HOOfrom 02/16/2022

Not exactly. Binning still occurs on monochrome CCD matrices before the ADC and serves to amplify the signal, but overall, the analogy probably works.
For the megapixels of a color camera, you either need to take the square root or trust somewhat deceptive algorithms like VNG.

Feb 17th, 2022

Evgeniy Sergeev

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

Cool that pixel math is now available. But the processing needs some work—the oxygen looks a bit unnatural, like a blob. The formulas are just for combining channels in HOO or SHO palettes. Since this was shot with a color camera, the oxygen signal is very weak. After combining with pixel math, I do separate processing for the oxygen and then blend it back using a mask. And it definitely doesn’t come together right away.

Apr 18th, 2022

BootleggerReply to Evgeniy Sergeev

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

I ended up on the page with the formulas from the video you recommended. Their main idea is to keep only the signal from oxygen where it dominates, which is why there's a bright spot. If you look at the many photos of the Rosette Nebula on AstroBin, it's clear that the area of oxygen dominance is captured correctly. It's just that with traditional processing, which proportionally mixes the signals from oxygen and hydrogen in the green channel, this region ends up with a whitish, pale color.

Apr 18th, 2022

AnatoliiReply to Bootlegger

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

Could you please share the link to the video as well?

Apr 22nd, 2022

AnatoliiReply to Bootlegger

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

And another quick question. In my setup with a Newtonian 200 f/5 + Sharpstar 0.95 MPCC + L‑Extreme, the stars are coming out elongated. I tried adjusting the backfocus and checked the telescope collimation, but I couldn’t fix it. Have you ever experienced this effect?

Apr 22nd, 2022

AnatoliiReply to Bootlegger

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

The stars are stretched uniformly across the entire field in a vertical direction. When I rotate the camera with the filter, the corrector rotates as well.

Apr 22nd, 2022

BootleggerReply to Anatolii

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

https://youtu.be/740ZLTe95eg

Apr 22nd, 2022

BootleggerReply to Anatolii

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

Oval stars are more often a mount issue than an optics issue.

Apr 22nd, 2022

AnatoliiReply to Bootlegger

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

But without a filter, only with a corrector, my stars are round, as they should be. Or without a corrector but with a filter. So it's not the mount's fault) Thanks for the answer.

Apr 22nd, 2022

BootleggerReply to Anatolii

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

Yes, it's unclear... This setup works fine for me.

Apr 22nd, 2022

AnatoliiReply to Bootlegger

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

Sorry again, a question. Do you have a 2" filter or a 1.25", and where is it placed—before the coma corrector or between the coma corrector and the sensor?

Apr 23rd, 2022

BootleggerReply to Anatolii

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

Filter 2", I shot in both configurations: the filter screwed onto the coma corrector and the filter between the coma corrector and the camera. It worked fine.

Apr 24th, 2022

AnatoliiReply to Bootlegger

NGC2237 Rosette Nebula in HOOfrom 04/17/2022

Thank you very much for the information.

Apr 24th, 2022