Globular cluster M13 (NGC 6205)

Posted: Mar 24th, 2021

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NGC

Technical Info

Telescope/Lens: Sky-Watcher Quattro 8CF

Camera: QHY163C

Mount: eq6Pro

Guide Scope: Svbony 60/240

Guide Camera: QHY5L-II-C

Software: APT, PHD2, Pixlinsight

Accessories: televue paracorr 2"

Exposure:

60 x 30" ISO/Gain: 0

60 x 60" ISO/Gain: 0

60 x 180" ISO/Gain: 0

Orange zoneLight Pollution:

Moskovskaya Oblast Ruza, Russia

Mar 23rd, 2021

4 h 30 m

2033

Resolution: 5292x4258 px

Scale: 23915 KB

Katafraht

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Comments

Smirnov Andrey

Good shot, but the channels are misaligned. This is clearly visible from the "tails" extending to the right and down from the brightest yellow stars.

20 Apr, 2021 Reply

Katafraht Replied to Smirnov Andrey

I still can't figure out the reason for such channel misalignment... the camera is color, after all.

21 Apr, 2021 Reply

Smirnov Andrey Replied to Katafraht

Indeed! I didn't notice that. Did you process it channel by channel, by any chance?

21 Apr, 2021 Reply

Smirnov Andrey Replied to Smirnov Andrey

It seems the issue is with the coma corrector. I just looked at the image channel by channel at high magnification, and the stars in the blue channel look like torn donuts. Nevertheless, the channels align well in Photoshop.

21 Apr, 2021 Reply

Katafraht Replied to Smirnov Andrey

No... I only extracted the luminance for deconvolution, and then recombined it through LRGB combination.

21 Apr, 2021 Reply

Katafraht Replied to Smirnov Andrey

No... I only extracted the luminance for deconvolution, and then recombined it through LRGB combination. Yeah, the corrector seems decent... I had the same issue with Baader too... Could it be due to the backfocus not being fully adjusted?

21 Apr, 2021 Reply

Smirnov Andrey Replied to Katafraht

It doesn't look like a streak; it's actually close to the center of the frame.

21 Apr, 2021 Reply

Katafraht Replied to Smirnov Andrey

Then I'll try tweaking the deconvolution parameters in PixInsight... that's probably where the issue is coming from.

21 Apr, 2021 Reply

Smirnov Andrey Replied to Smirnov Andrey

Hmm... I was thinking: how was the camera oriented? By any chance, is that elongation not vertical? If so, it looks like atmospheric dispersion.

21 Apr, 2021 Reply

Katafraht Replied to Smirnov Andrey

90-degree orientation...