NGC 4631 / C32 The Whale Galaxy

[x6gas]

Hi all,

Here's a couple of renditions of NGC 4361 / Caldwell 32 the Whale Galaxy in the constellation of Canes Venatici.

Kit: Esprit 150; Atik OAG; Atik EFW2.2; Astrodon filters; Atik 460ex; iOptron CEM60EC

Data: 300s subs (R 61; G 57; B 55) for a total integration time of 14.4 hours.

This has taken a good while to process mostly because I'm still learning and experimenting with PixInsight; as we all know it's a powerful program but I want to try to understand what I am doing rather than just follow recipes blindly and it's hard work because the documentation is frankly terrible (some of it is ridiculously detailed and complex and other basic things aren't covered at all... as a result some of the online tutorials are misleading or just plain wrong so it's difficult to know what is trustworthy - sorry, rant over!)  In this image I bunged all of the subs into the stacks just to see what would happen compared to being more selective.  The data was pretty patchy too with quite a few subs taken in lightening skies and a couple that had tracking errors.  I did finally get some positive results using deconvolution following the excellent tips on Jon Rista's blog (never had any success with deconvolution in AstroArt no matter how hard I tried).  I am going to reprocess the data with tightly selected subs to provide a comparison and I'll post that when done.

This one is a little more gentle in all respects:

Thanks for looking.

Ian

Edited May 25, 2020 by x6gas
typo in NGC catalogue number in title

[JoshHopk]

Gorgeous, well done Ian 

[tooth_dr]

Very nice, good looking galaxy, I like the slightly stronger first version.

[x6gas]

Thanks Josh.  Needs patience at this time of year doesn't it - clear skies but no astronomical darkness.  I suspect that when I reprocess this and am a bit more picky with the subs I use I'll be down to 2/3rds or even half the total data...

 

[x6gas]

1 minute ago, tooth_dr said:

Very nice, good looking galaxy, I like the slightly stronger first version.

Thanks Adam.  I think I do too, but I generally like to try to process things to look au naturale.  Actually I was going to post an even racier (for me!) version but I decided I was getting addicted to increasing saturation and vibrancy so dialled it back a bit (sometimes less is more...!)

Clear skies mate!

[Xiga]

This is good, very good in fact! 

I've had a go at this myself (with all the wrong equipment, i won't share it, lol) so i can speak from experience. I prefer the 1st version, and i wouldn't mind seeing the racier version either. Colour saturation is always a personal thing, but for me i find this target to be one that lends itself well to a higher level of saturation. 

Edited May 17, 2020 by Xiga
spelling

[MarkAR]

Excellent images, one of the best whales I've seen.

Pixinsight can be very daunting and following someones workflow can get you into trouble. For many things it's a case of what exactly needs doing in each process in MY image. It can be very different to someone else's even using the same tools.

There are also numerous ways to do many processes and deciding what works best can be difficult so there's a lot of experimenting and backtracking involved.

[x6gas]

10 hours ago, Xiga said:

This is good, very good in fact! 

I've had a go at this myself (with all the wrong equipment, i won't share it, lol) so i can speak from experience. I prefer the 1st version, and i wouldn't mind seeing the racier version either. Colour saturation is always a personal thing, but for me i find this target to be one that lends itself well to a higher level of saturation. 

Thanks Ciarán, much appreciated.

So you've tempted me into it.  Here is the full beans version.  Well I say that, but actually it doesn't look too garish to my eyes this morning and of course it's always possible to keep pushing the saturation... perhaps I'm just too conservative!

 

[x6gas]

8 hours ago, MarkAR said:

Excellent images, one of the best whales I've seen.

Pixinsight can be very daunting and following someones workflow can get you into trouble. For many things it's a case of what exactly needs doing in each process in MY image. It can be very different to someone else's even using the same tools.

There are also numerous ways to do many processes and deciding what works best can be difficult so there's a lot of experimenting and backtracking involved.

That's very kind of you to say Mark - especially since the Whale has been a popular target with some excellent images posted on here.

I know what you mean about following other people's workflow for PI and the problems that can cause.  It's why it's so important for me to know what fiddling with the mind-boggling array of parameters actually does as opposed to random experimentation (which would take forever).  I find the UI/UX to be quite poor - it feels like it has been written by coders with little regard to ease of use (for example not allowing spaces in naming conventions, lack of separate easy and advanced selection panels etc., etc. and as I say very patchy official documentation).  All that said, I don't underestimate how hard it is to create something as complex as PI; it is extremely capable and the creators have to be given great credit - not least for the care they have taken to preserve data integrity.  I am enjoying getting to grips with it...

[Xiga]

2 hours ago, x6gas said:

Thanks Ciarán, much appreciated.

So you've tempted me into it.  Here is the full beans version.  Well I say that, but actually it doesn't look too garish to my eyes this morning and of course it's always possible to keep pushing the saturation... perhaps I'm just too conservative!

 

I quite like that Ian. Perhaps v1 stars with full beans Whale? 😅 Or just tone down the reds a bit?

Maybe I just like beans too much...lol

[x6gas]

Thanks for all the comments and likes.

I managed to capture a few more subs last week and I've done two complete reprocesses.  In total I captured around 80  subs for each channel but the SNR was low in many of them as the sky was getting quite light. 

The first reprocess used the best 50 frames of each channel (so a total integration time of 12.5 hours) and I've done a couple of versions:

 

I was still a bit bothered about the star shapes (the Esprit 150 is getting near the limit for my CEM60) so for the second reprocess I selected the best 35 frames for each channel (total integration time 8.75 hours) specifically refining the eccentricity value of each frame... For some reason this data set was quite hard to process as - oddly enough - I had trouble stretching the RGB file: a good stretch on the galaxy was leaving the background sky very, very dark.  I've never had this before...  Anyway, another couple of renditions.

As ever there are things I like about all four versions and I'm having a tough time deciding on my favourite.  I have enjoyed processing this object - and I've learnt a lot about PixInsight (even more on the reprocesses and I adopted new processes, different stacking parameters, normalisation, subframe weighting etc., etc - and it's nice to see small galaxies captured all over the frame.... but I'm done now!  I've been staring at it too long and I've got other targets to process so I'm calling these final.

Thanks for looking, take care, and clear skies.

[MarkAR]

Well done, I think I like 1 and 3 the best.