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Old 17-12-2022, 05:21 PM
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AstroViking (Steve)
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NGC2070 - Tarantula Nebula Recaptured

Hello all,

OK, a bit of a long(er) post here. Then again, maybe not...

As you're aware, I picked up an Optolong L-Enhance filter for my astro setup a while back. Because of the weather (way too many cloudy and/or rainy nights) I haven't been able to get any imaging done. However, we've had a couple of clear nights (and a couple more are forecast) so I had the rig out last night and imaging away.

I chose to do the Tarantula Nebula (NGC2070) again to compare how it looks through the filter when compared to my previous attempt. (Hey, nothing like a bit of scientific method, eh??)

However, I also did some reading about why I was getting such a massive blue-shift on my images. Well, it turns out that the ZWO cameras have two in-camera white balance controls - WB_B and WB_R. WB_B is for the BLUE channel, and WB_R is for the red channel. The default values (on a scale of 0 - 100) are 95 and 52, respectively. So, any guesses as to why my images were having a fit of the blues?

The ASCOM software for Windows has it's own white balance values so the default values are never seen. As I use KStars/Ekos for my imaging, the default white balance values are used. Once I set the WB_B and WB_R values to 50, the images suddenly looked a lot, lot better.

One other impact of having the filter is that I can now do much longer images. The images below were taken from a stack of 180, 30 second exposures, for a total of 90 minutes of integration time.

I have a lot further to go with my imaging and processing work, as there is a lot of red noise in these images. I've hidden it reasonably well, but someone with sharp eyes will be able to see it.

As always - comments, critique and feedback are very welcome!

Cheers,
V

Gear: SWED72 @420mm / ASI183MC-Pro / HEQ5 / SV305 + SV165
Software: KStars / Ekos

Image details:

* Gain: 50
* Offset: 10
* Temperature: 0 degrees C
* Exposure: 30 seconds
* Lights: 180
* Darks: 25
* Flats: 25
* Dark Flats (Bias): 25
* Stacked and proc'd in Affinity Photo
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Click for full-size image (NGC2070.jpg)
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Old 17-12-2022, 06:24 PM
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Nikolas (Nik)
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keep adding to it mate the more data the more detail, colours are lovely
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Old 17-12-2022, 07:36 PM
oska (John)
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Great depth Steve. A few more hours and you'll get the noise out of the faint bits (scientific term) too. Well done.
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Old 17-12-2022, 09:45 PM
Dave882 (David)
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Great work there’s a real depth to the detail to your image!
Is it just my screen or does there seem to be some horizontal banding coming through? Maybe might be fixed with more data but may be worth checking your calibrations are ok…
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Old 18-12-2022, 11:04 AM
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AstroViking (Steve)
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Thanks gents!

This is the first image with the ASI183 that I'm really happy with. Yes, there is room for improvement - there always is.

David - yes, there are horizontal bands, although I did my best to hide them. When I stacked the data in SiriL, they were most visible in the red channel. The Affinity Photo stacking routine did a much better job of removing them, but they were still present. We'll see how last night's data of M42 goes.

Cheers,
V
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