M81 - Fighting through the LP

[badgers]

Hi Everyone,

It's been an age since I've been imaging... it seems every time I get clear skies its a full moon or I'm due to travel for work.

I've put my little refractor away for a few weeks and have my trusty Skywatcher 150P back in action again for some galaxy work.

This was the first part of a 2 panel mosaic I'm working on for M81 and M82.

I'm already 350 minutes into this project, Over 3 hours of luminance and 2 hours RGB.

The images seem very noisy indeed, I'm guessing this is a difficult target with Light Pollution, although its so long since I used the Newt I hope the collimation is within reasonable limits.

Anyway, I figure I'll need darker skies or a lot more time to do this justice, but here's part 1 anyway.

Any advice on how to improve this would be much appreciated. The stunning images I see online for M81 seem to be from large aperture scopes in pristine skies, so I'm hoping this isn't too bad of a start from city skies.

Thanks,

Anton

Minimal processing here, some DBE for a nasty gradient in the Red filter and a little noise reduction and curves.

Here is the luminance only image, noisier than I am used to with this camera.....

[michael.h.f.wilkinson]

Very nice indeed

[Mr Bergman]

Very nice!

[peter shah]

nice and crisp some stunning detail

[badgers]

Thanks guys,

I'll keep adding some photons to this and see if the noise drops off, I'll try and get out of Cambridge to somewhere darker at the weekend.

Anton

[Daniel-K]

keep going!!! this is my favorite galaxy you have some super detail, MORE SNR!!!!!!

[Black Knight]

Very nice Anton. Looking really good with great stars

[ultranova]

Nice Anton, the luminance image is sharp, lots of detail coming through,

I dont think it my screen but you have a green thing going on in the arms of M81

The core looks fab, do you use a LP filter, I can not image at all with out mine.

[badgers]

Thanks, yes the colour is off for sure I need to pull back the green.

I used to image everything through a UHC-S filter from Baader but it was very hard to get correct RGB balance back, although it really helped cut the glow.

Now I shoot luminance through an IDAS-LPS filter but I'm not filtering RGB any more for LP. I've an idea the red channel is picking up sodium glow as there is a gradient left in that channel even after flats.

Thanks,

Anton

[RobH]

Lovely image. As yopu say, it needs more time to get the noise down, but it's really nice and tight and will only get better

Cheers

Rob

[Gina]

Very nice indeed Anton

[Scott]

love it

[badgers]

Another 3 hours captured last night on the luminance putting me at 6 hours L. I think I need another few hours.

The RGB needs more time, I might try getting 2x2 binned data, although I usually go 1x1.

The new luminance has much less noise just need some new RGB to back it up before I repost.

In the meantime here's a little noise animation going from 5 minutes to 6 hours.... amazing how much time this one is taking.

[Scott]

Thats a great animation there Anton. As they say... A picture (or a series of them) paints a thousand words.

It really shows the need for "more data" (regardless of sub length) is the key to quality imaging and something not to be taken lightly.

[ultranova]

Love the animation Anton, shows how more subs cancel out the noise

Quie a few people on here bin there colour at 2 x and looks perfect

so it might be worth having a go.

Well done Paul.

[sologuitarist61]

Beautiful detail in there - very good indeed

[cfpendock]

This kind of animation I find really useful. Thanks for posting. And I think your stars look very good.

Chris

[badgers]

Thanks again for the advice and encouragement.

I've added last nights RGB.

First time I've tried binning colour 2x2, It definitely doesn't look as clean at high zoom, but it certainly gathered more colour.

I've chronic gradients that only appear in the red channel... Not sure what to make of that, but it's making colour balancing hard.

My theory is a light leak between the focuser and the tube being hit by a sodium light about 10 feet away..... Nobody said city imaging would be easy : (

Light leakage seems to be an often overlooked bane in newtonians...... Flats from my refractor generally look beautiful, they are much more random on the Newt.

This is now:

200 minutes Luminance in 5 minute subs

160 minutes Luminance in 10 minute subs

30 minutes RGB in 5 minute subs (1x1)

50 minutes RGB in 5 minute subs (2x2 binned)

Total 6 hours L and 4 hours RGB.

I've changed from a Skywatcher Coma Corrector to a Mark III Baader MPCC corrector during the RGB capture, the new corrector seems to be working flawlessly at the same spacing.