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Damn... galaxies are hard!!!


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After about 4-5 months without any imaging and precious little observing I've finally managed to get back out there under the stars. Attached is a luminance image of M33 taken whilst at the South West Star Party in Exmoor last weekend. Despite a huge amount of mud and rain early on we were treated to a fantastic clear night on the Saturday...

Taken through my Borg 77EDII @ f/4.3 using a Starlight Xpress H694 the image is 29x 5min subs. Processing has been fun... I'm more used to nebulae and as galaxies go M33 is an odd one. Whilst there is noise in the image it turns out that M33 itself looks 'noisy" and too much processing out of this noise actually ruined the image - I've processed this several ways and have ended up throwing out most of my efforts and have posted a version with about half the processing my original effort had!

I also need to work on my spacing slightly - the image is pretty flat but the corners need seeing to, I think I'm still a little out on the spacing between the reducer and the camera.

RGB is the next challenge for this one...

Details:

Mount: EQ6 via EQMac

OTA: Borg ED77II @ f/4.3

Camera: Starlight Xpress H-694

Guiding via Lodestar and Nebulosity (Side by Side)

Data Capture: Nebulosity

29x 5 min subs

Stacked and processed in PixInsight

Enjoy (I hope!)

James

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EDIT: Strewth... I hate what Jpegging does to the image .. :embarassed:

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Well that looks a cracking luminence to me James. Sometimes posting seems to affect the image a little but it looks ok to me. Completely agree that this is a tricky galaxy to process, it's blotchy and those faint trailing arms are very tricky. I think it was badly processed at some point during it's creation!

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That looks like some cracking luminance for starters - M33 is very tricky as I found out myself. In fact I agree with you and think that galaxies are just hard to process, full stop!

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You're right about the naturally noisy look of this blighter. It is curiously speckled. I know it doesn't go away because over the years and several imaging runs I have gathered enough data to sink a ship and it never goes smooth. Yours looks splendid.

One thing; in the smaller image you have a (slight) dark halo around the galaxy. I got this as well as did another recent M33 imager. I think it is caused by having the background samplers too close to the galaxy in DBE. It's less obvious when you see the larger one. Could this be the case with you? Did you use DBE?

Olly

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I did Olly - that'll teach me to use DBE rather than taking flats... I'll give it a try later with the indicators further away :smiley:

@ Gina - thanks for the tip - I'll try PNG next time :smiley: It'll be a larger file size though I suspect so the mobile phone brigade won't like it :grin:

James

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I did Olly - that'll teach me to use DBE rather than taking flats... I'll give it a try later with the indicators further away :smiley:

@ Gina - thanks for the tip - I'll try PNG next time :smiley: It'll be a larger file size though I suspect so the mobile phone brigade won't like it :grin:

James

DBE might correct it as it is, maybe?

Olly

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@Olly - I'll give it a go at the weekend :smiley:

That borg seems to be working nicely, what do you think of it?

Rather a lot actually... I'm really looking forward to tackling some of the bigger nebulae that I'll get a chance to get now (the Soul Nebula is waiting for me for starters...). The scope is light, the field is flat (and will be perfect once I've adjusted the spacing).

With it being modular I have already run into a problem though... I'm now dreaming of getting the whole of M31 on the CCD and the 60ED f/4 version is winking at me. Also with the scope being so light it wouldn't be hard to mount two, or even three of them on a decent bar... I know someone with the technical expertise to get that all up and running but I suspect I'd be going without pay for a little long while :rolleyes::embarassed:

James

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lol :D Im sure i could sort something out if you needed it :) I like the idea, i wonder what Steve and Kate think of it though :) Im really looking forward to seeing some more from this lovely little thing.

It really does seem like a great little scope, I love the adaptability of it, and the quality of the optics are living up to their reputation.

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  • 4 weeks later...

Well, so far nothing has caused me to rethink the title of this thread... :rolleyes:

I've now got a colour image :grin: I've added in one hour each of red, green and blue. I've started collecting Ha but have only two subs so far...

I've had a right time trying to get the colour in what I think is correctly - M33 is obviously not the most colourful of galaxies and just prior to posting this updated image I noticed that I've done my masking wrong and my star masks have been masking out some of the areas of the galaxy that have a trace of red in them. Either way, I'm actually quite happy so far..

Here's M33, this time LRGB, L 19x 5min, R, G & B 12 subs each of 5 minutes. Next clear night I'll start getting more Ha if moonlit, if not moonlit then I'll try for more colour subs - although I'm wondering if getting more colour will just be a case of rapidly diminishing returns?

I'll also need to reprocess to correct my star masks...

James

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