NGC6744 / Caldwell 101

[AstroViking]

Hi all,

I got a chance to hit a dark sky site on a clear night (Yay!). Whilst 2 hours of data is pretty good (the longest I've ever captured), it wasn't enough to do justice to this one. The focal length is a bit short, too. 30MLY is a bit of a stretch for this scope, I think.

I'm not happy with this result - it's far too noisy and you can't see the detail in the galactic arms & core.

But hey, them photons travelled for that long, it's a shame to waste them.

Cheers,
V

SkyWatcher EvoStar72ED @ 420mm
Nikon DSLR
120 subs of 1 minute each @ ISO 3200 (bad move - way too much noise)
50 darks (no flats / bias)
HEQ5-Pro w/ SV305/SV165 guiding
Stacked in Siril, processed with Affinity Photo

[i.baker]

Looking good Steve, I see you've got some new equipment since we last talked (sorry I recognised your profile pic from work :) )

[AstroViking]

Hey Manny!! Good to see you here.

Yep, did some upgrades over the last few months. Still getting the wrinkles out, and running into the next set of speed bumps.

[AstroViking]

Now, I've just gone back and reprocessed this one. Found some bias frames, created some flats that may or may not have done anything useful, the fed everything back into Siril.

This time I chose the 'Drizzle' option and watched the CPU meter peg at "She canna go any faster captain!".

The result after much swearing in Affinity and a judicial resize is attached.

Cheers,
V

[Dave882]

Nice job Steve! A few more hours will help with the background noise, but in the meantime you’ve managed quite a good result :thumbsup:

[xelasnave]

Great result Steve ...don't think about what you didn't get think about the chickens in the
nest.

Alex

[AstroViking]

Thanks for the kind words, guys - much appreciated.

Alex - you said somewhere else that there will always be photos better than mine. Therefore the essence of it all is to keep a balance and be happy with the (relative) miracles that we all create with each photo.

[AstroViking]

Hi all again,

I thought I'd try the "No Histogram Stretch" with Siril and had a go at reprocessing. To my eyes, this one looks a bit cleaner in the core of the galaxy.

What are your thoughts?

Cheers,
V

[xelasnave]

I like the very first image overall.
If you want us to compare perhaps put up two 8n one.
Alex

[Crater101]

Really liking the way this is going mate, certainly better than anything I'd be game to post. Nice work.

[Dave882]

Nice one- you’ve revealed some nice structure in the galaxy. I think I like the colours of that last one and it’s certainly a lot cleaner than the 2nd one. Can I suggest one thing- by my eye I can see a repeated pattern in your stars with a bit jutting out to the left. I reckon this could be caused by a couple of rogue subs with a bit of a jump in the tracking. If you do a cull of some subs with poor star shapes prior to stacking I think it could end up quite a bit cleaner.

[Stephane]

Great job Steve. The great thing is that this galaxy isn’t going anywhere any time soon. You can add data to this whenever you please; that is, whenever the weather is favorable.

[AstroViking]

Evening all,

Thanks very much for the feedback. I am still finding my feet (so to speak) with the processing, so each image will have been mangled in a slightly different manner. Hopefully I am mangling them better each time.

David - I can go back through the subs and have a closer look at them to see if any are a bit odd. I was not using the reducer/flattener with this one, so the stars got very stretched on the outer portions of the images. What you see is a 1920x1080 crop of the centre of a 6000x4000 image. If I can find a way to crop the centre portion of each sub, then I might have more luck at spotting the odd ones. (I don't fancy the prospect of eye-balling each sub. Not at the moment, anyway...)

Warren - I haven't been doing AP for very long. If I can do this, then so can you! (Seeing the quality of the images posted here can make it difficult to submit your own work - it took me a long while to find what I felt were my best images and upload them.) So show us what ya got...

Cheers,
V

[Stephane]

Steve, you can be proud of your image and you are showing some nice signs of progress. I second Dave's comment about the repeated pattern. Have a look. Also, when applying colour saturation, I suggest the use of some kind of mask (perhaps a luminance mask or range mask) so as not to saturate the background. This will give the image a cleaner look.

Again though, great effort. Some nice detail and colours there.

[xelasnave]

I am having a go at this one right now...I noticed it on Sky Safari and went for it but I did not realise it was what you shot even after commenting:P...anyways I am getting some luminance 100 gain 30 seconds and I guess RBG later..I selected it cause I only had to open the roof half way:D.

Pretty small so you have done well.

Funny we dragged the RASA out of the way of putting in the piers today and I have not done a new PA:eyepop: but it is managing thank goodness as I am beat and just wanted to get it running and have a nap after I finish my cuppa.
Alex

[AstroViking]

David, Stephane, that's excellent spotting on your parts. Thank you!

I went and looked through some of the subs and you are correct - a lot of the stars have a "ghost" star a few pixels to the left. That would explain the not-quite-round stars. Rats.

I had massive issues that night getting things working and ended up recabling everything (twice) to get it running. I suspect it might be cable drag, or poor guiding as the guide camera preview was a mess of over-exposed pixel noise. Or both...

I'll go and have a look through my most recent NGC55 subs to see if the ghosts are back. If they are, then it's something more serious I need to resolve...

Thanks again for the feedback!

Cheers,
V

EDIT: Have checked the NGC55 subs and no ghosts present. So it was something on the night that caused the problems.

[Stephane]

I occasionally get those kind of subs too Steve. When weighting my subs they often get picked up, but not always. So I manually inspect all my subs one by one using dedicated software for that purpose. It’s a long process, but a rewarding one as you get to hand pick the very best subs to go into your stack.

[Dave882]

Yeah it happens to all of us mate. Could have been balance, cables or even wind. I use ASI STUDIO - it’s free and they have a Fits Viewer which performs an auto stretch and you just flick through each frame with one click to delete. Takes me no more than 10min to go through a few hundred subs.