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My second attempt at DSO imaging (M13, M31, M39, M57 & IC5146)

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It's been a short while since I posted by first three DSOs (about a week), so I figure it's about time I crack on with the next batch of targets.

Tonight: M13, cluster in Hercules; M39, an open cluster in Cygnus; M57, the Ring nebula; IC 5146, the Cocoon nebula and M31, the Andromeda galaxy.

I used the following equipment:

Skywatcher 150P on a HEQ5 PRO mount

Canon EOS 1000D (unmodded) @ ISO 800

Skywatcher Light Pollution Filter + Baader MPCC

I polar aligned in my garden for the first time ever! (I successfully found a spot where I can see Polaris). All shots are unguided and I used the SynScan "2 star align" process which allowed me to track fairly accurately, at least for a newbie like me just starting out.

I took the following calibration images:

BIAS x 20

DARKS x 10 (45 second @ 10 degrees celcius ambient temp.)

FLATS x 20 (white [new!] boxer shorts placed over scope & floody LED torch illuminated from a distance)

The sub data:

IC 5146 Cocoon Nebula = 21 x 45 seconds

M31 Andromeda Galaxy = 30 x 30 seconds + 5 x 60 seconds

M13 Cluster in Hercules = 10 x 30 seconds

M57 Ring Nebula = 20 x 45 seconds

M39 Open cluster in Cygnus = 10 x 45 seconds

Now I know that I've spread my total imaging time over a variety of targets but I wanted more than anything to test a variety of exposure times and targets to get a 'feel' for a variety of objects and the 'seeing' conditions on what is the clearest night in Farnborough that I've seen before.

I am generally quite happy with the view on Andromeda although I understand that this, like the other objects in my list tonight, require a great deal more time. However some objects like the Cocoon Nebula leave me feeling like I've totally missed them since I cannot make out any nebulosity at all.

I stacked all the images in Deep Sky Stacker and other than increasing the saturation by approximately 10-15%, all the options are the defaults.

Criticism is welcome and encouraged, especially if you know how I can make my images look better in post processing!

IC 5146 - Cocoon Nebula


M13 - Great Cluster in Hercules (cropped)


M31 - Andromeda Galaxy


M39 - Open cluster in Cygnus


M57 - Ring Nebula


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The 2 star alignment will not help you track any better - it helps the goto work more accurately.

I am not surprised that the Cacoon shows little - the DSLR is not ideal for that type of object.

I think that there is more data in the M31 and M13 images. The ring nebula is excellent!


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I think you have a lot more data hiding in these files than can be seen.

Look at DeepSkyStacker - User's Manual "Adjusting the Luminance Curve". The peaks you see correspond to the sky background. You want your curve to rise sharply just above the peak like in this image ProcessingTab.jpg

There's a hint of trailing in some of these and the focus may be slightly off, too. As you're finding out, getting these two right takes a long time.

If you want a quick way of estimating your Polar Alignment error, I have a photographic method that works.

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I agree with Themos, you had gathered enough data to show more of the beauty of these objects. Especcially with M13 and 31! They both are bright objects and your setup is powerful.

If you have PS then this tutorial can be in help:


It is a set of easy and to follow steps.

Here is very fast applying of these steps (plus little tunning of right border in Levels before Curves) over your image. Imagine what you can get out with the original stack result :)


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Ant, Thermos, Yhodda,

Thanks for your advice!

I'm intrigued by that M13 image - wow. I can hardly believe that I took that! I will take a look at those tutorials and reprocess.

Thermos - I'd like to hear more about your photographic alignment method please!

Another question - if I take more subs tonight, but from a slightly different location and at a colder temp, can I add these new images to a stack of last nights images -or- process a new image with only new data and then merge the two 'final' images together?

Lunchbreak coming up, I'll read up!



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In DSS you can define two groups and then to stack all data at once. If you want get wider field in the final image, when you frame the object try place in the close to the previous position and to orient the camera by the same way as the previous night. Disposition and different orientation will give result where only the intersecting area is usable.

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Thanks Yodda and Thermos,

I don't think I'll be able to get my camera mounted in the same angle as last night, but I'll give it a go. What I may end up doing is just trashing all my old work and starting again from scratch with some longer subs to see how long I can go before my non-guided tracking fails me.

As for the Polar Alignment via camera - that's a neat feature. It's something that I will probably end up doing in the future (e.g. after the construction of a pier) as I don't think I'll want to be going through those steps every night :)

Thanks again for the insights :)

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Oh my goodness! *jumps up and down, rapidly drooling*

I followed the instructions on stretching the histogram/adjusting the curves and levels in Photoshop and may I present to you, the Andromeda Galaxy!


I am amazed that I can actually see the dust lane. Incredible given the scale of the light pollution here!

Imaging will continue tonight in earnest :)

Photoshop tutorials: How to stretch the histogram using levels and curves

Astro Imaging Tutorial Learning to Use Photoshop Curves

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I think I've just figured out what the cotton-nebula like texture is on the image (mostly noticable at the bottom right).

It's the fibres from my pants (boxer shorts) that I used to take my flats with.

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Well done Mike, you are doing great, and it's your enthusiasm that's infectious. You will go a long way mate. Great stuff, and I love your sense of humour, it's that kind of attitude that makes this forum tick.


Edited by barkis
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Thank you all for your encouraging words and suggestions for improvement.

Tonight I have managed to get the evening to myself and four hours earlier, WeatherPro/Sat24 had been forecasting clear skies.

I head outside to polar align and it seems I took too long, as Polaris disappeared behind a long band of cloud while I was fiddling with the date/time circles :)

I remain optimistic for a reprieve in the cloud situation before midnight.

Fingers crossed!

edit @ 23:15: Why does astronomy have to be so damn complicated? ;P I've just been trying to do a star align for GOTO (I know I don't need to, but I was frustrated because I couldn't) and I kept seeing "RA align > 45 degrees" messages by the time I got to my second or third star in the alignment. I couldn't figure it out - I thought I had used by "Alt-Az" handset instead of my EQ one. And so I decided to park the scope and come inside for a nice warm cup of tea - and then I noticed the scope's RA axis wasn't parking in the correct position (scope pointing to polaris), but it was off by... about 80 degrees. Once I parked the scope and used the clutches to correct the park position, I was able to successfully align.

I wonder if I'll get any imaging done tonight. I might go out and do some darks and flats in anticipation of the cloud clearing. But only after I've had a cup of tea.

Edited by MikeWilson
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