NGC 3621 - delicate low surface brightness galaxy in Hydra

[strongmanmike (Michael)]

Originally Posted by LewisM

Its the aviator in me

Ah I see, thanks for the comments

[graham.hobart (Graham stevens)]

An awesome spectacle on the big version Mike. Really lights up and the background fuzzies are amazing, give it a nice perspective.
Surely a book of your pictures can't be far away!!

Graz

[strongmanmike (Michael)]

Ah thanks Graham one mans "lights up" is another mans "Garish"

Book?...yeah, maybe one day...



Mike

[RickS (Rick)]

Originally Posted by strongmanmike

there are tell tale signs of de convolution remaining on the stars, ... I know the theory is probably sound but I always doubt the accuracy of deconvolution and how people apply it, how does the filter know to shrink a feature so that it remains the actual shape it should be rather than just get shrunk to a point with arbitrary or in fact differing shape and thus simply creating more of an illusion of higher resolution...?

Mike,

The theory is sound and so long as you know the point spread function it should work perfectly. In practice you have to estimate (or guess) the PSF. Also, the decon implementations in packages like PI and CCDStack can only deal with a single global PSF when in real life the PSF can vary across different parts of the image.

Still, you can get reasonable results in PI so long as you have data with good SNR and don't push it too far. It has a nice tool, DynamicPSF, which helps estimate the PSF.

Cheers,
Rick.

[Stevec35 (Steve)]

Pretty good effort Mike. It's a deceptively difficult galaxy this one.

Cheers

Steve

[Logieberra (Logan)]

Mike.Nice! How you enjoying the seeing out that way? Any stats? How does it compare to the Cbr burbs? Darker, no doubt

[SkyViking (Rolf)]

Beautiful image of a beautiful galaxy, Mike There is a lot going on in that image and it seems you captured all the faint outer parts. Some interesting background galaxies too, and the little spiral above is cool
It could be very interesting to see a side-by-side comparison with a version from your FLI.

[astronobob (Bob)]

Grouse one Mike, , amaizing details in the Galaxy central dust lanes ! Im flat out getting such in Andromeda
Always dig your colour processing aswell.
Another Mighty fine show of your work

[strongmanmike (Michael)]

Originally Posted by RickS

Mike,

The theory is sound and so long as you know the point spread function it should work perfectly. In practice you have to estimate (or guess) the PSF. Also, the decon implementations in packages like PI and CCDStack can only deal with a single global PSF when in real life the PSF can vary across different parts of the image.

Still, you can get reasonable results in PI so long as you have data with good SNR and don't push it too far. It has a nice tool, DynamicPSF, which helps estimate the PSF.

Cheers,
Rick.

All my understanding too...

But in a nut shell, if not applied using area/feature specific valid PSF's it is indeed creating an illusion and potentially simply making small bright irregular shapes in, say a galaxy arm, into small dots with new shapes that when viewed as a whole makes an image or area of an image look sharper but it is no longer the real detail as it were ...I'm still out on this but granted when applied well it can make the image look higher res, so I guess that's part of it anyway

Originally Posted by Stevec35

Pretty good effort Mike. It's a deceptively difficult galaxy this one.

Cheers

Steve

Yeah quite a faint outer arm area with this one

Originally Posted by Logieberra

Mike.Nice! How you enjoying the seeing out that way? Any stats? How does it compare to the Cbr burbs? Darker, no doubt

Hi Logan, hard to scientifically quantify seeing, even when scouting for pro observatories, so anecdotal is the best we can do I guess...and with this in mind I think the seeing here at Wallaroo is probably about as good as I remember Canberra being when I was imaging from Campbell during the second half of 2006, maybe marginally better? It was probably a little better seeing and more consistently so when I lived at Googong though, where I was at almost 800m ASL imaging with the Starfire during 2004-2006 (was a drought on). It is obviously noticeably darker here at Wallaroo than Campbell and about the same as Googong although when I lived in northern Ngunnawal in 2002 the skies there were quite dark except to the south and the seeing again was about as good as here ie some good nights some crap I did have a good handful of nights with what I would class as exceptional seeing at Googong but so far, although I have had a few nights I would call good, I have probably only seen one or two nights from Wallaroo that I would describe as getting close to exceptional seeing and that was the nights I did THIS image and THIS image.

Tis certainly rather windy here (did I ever mention that )...but the dome stopped that issue in its tracks

Not sure all that was really all that meaningful but I can say this - as far as seeing goes, all sites I have used in the Canberra region are better and more consistently so than anywhere I imaged from around Newcastle between 2008 - 2012 and excellent dark skies are only a 20min drive beyond the edge of Canberra but are only found driving much further from Newcastle and even then they are not as good.

Originally Posted by SkyViking

Beautiful image of a beautiful galaxy, Mike There is a lot going on in that image and it seems you captured all the faint outer parts. Some interesting background galaxies too, and the little spiral above is cool
It could be very interesting to see a side-by-side comparison with a version from your FLI.

Cheers Rolf it came out ok in the end I guess and seems to compare favourably with the few examples available on the net done with larger longer FL scopes.

What are you thinking with the FLI?...less resolution..? Maybe I should image something I did with the ProLine from here just to compare...? Have you heard of the Antennae galaxies by any chance maybe I should do those with the new setup?

Originally Posted by astronobob

Grouse one Mike, , amaizing details in the Galaxy central dust lanes ! Im flat out getting such in Andromeda
Always dig your colour processing aswell.
Another Mighty fine show of your work

Thanks Bob, love your easy attitude and warm candour, should be more of it on here

MIke

[SkyViking (Rolf)]

Originally Posted by strongmanmike

What are you thinking with the FLI?...less resolution..? Maybe I should image something I did with the ProLine from here just to compare...?

Yeah, just thought it might be an interesting experiment, having a direct comparison between the two imaging systems. Maybe the newer chip is better, less noise etc. but on the other hand the FLI has more cooling.

Originally Posted by strongmanmike

Have you heard of the Antennae galaxies by any chance maybe I should do those with the new setup?

I vaguely recall the name Actually I'm having a rather intimate relationship with these very galaxies at the moment, lol. Around 25 hours collected so far, but more to come of course.

[strongmanmike (Michael)]

Originally Posted by SkyViking

Yeah, just thought it might be an interesting experiment, having a direct comparison between the two imaging systems. Maybe the newer chip is better, less noise etc. but on the other hand the FLI has more cooling.

Problemo is that I don't have a OAG solution available for the ProLine+AG12 combo

I vaguely recall the name Actually I'm having a rather intimate relationship with these very galaxies at the moment, lol. Around 25 hours collected so far, but more to come of course.

Yeah I knew you were stealing all the photons from Paul on this one

Sounds like it will be spectacular...wish it was easier to collect mega data ...or I could find the concentration and will again

Mike

[SkyViking (Rolf)]

Originally Posted by strongmanmike

Yeah I knew you were stealing all the photons from Paul on this one

Sounds like it will be spectacular...wish it was easier to collect mega data ...or I could find the concentration and will again

Mike

I'm sure there are enough photons to go around
Or did I notice a brief darkening of the sky when I pointed my scope upwards yesterday night...

[alpal]

Originally Posted by strongmanmike

Ah nah, it's all good, differing opinions is a healthy thing as long as we don't get too wound up and cranky ()

As for Robbo's image and I'm not criticising juuuust observing , there are tell tale signs of de convolution remaining on the stars, they are bright points inside more defuse discs and the background is evenly speckled, the gradients are pretty obvious too I know the theory is probably sound but I always doubt the accuracy of deconvolution and how people apply it, how does the filter know to shrink a feature so that it remains the actual shape it should be rather than just get shrunk to a point with arbitrary or in fact differing shape and thus simply creating more of an illusion of higher resolution...?There is also a magenta hue to the core area too..ok, ok sorry Rob not being critical it was an APOD after all

Mike

Hi Mike,
I would say that deconvolution applied to high signal to noise ratio areas
definitely increases the correct detail.
In low signal areas it tends to make a false grainy look that can only
be remove by adding noise such as in this helpful example:

http://bf-astro.com/backgndRepair.htm

I used this technique on my NGC 1808 galaxy background
on flickr which had super high noise.
Stars & low signal areas should be masked when applying deconvolution.


cheers
Allan

[strongmanmike (Michael)]

Thanks for that Allan, had seen that article before but never put it into practise...must have a go on one of my uncalibrated images

Mike

[tilbrook@rbe.ne (Justin Tilbrook)]

Wonderful image of 3621 Mike!

Like the strong colours, I think it really defines regions in the galaxy.

Cheers,

Justin.

[strongmanmike (Michael)]

Hey thanks Justin and glad you like the garish colours (meah, like olives and anchovies either love'em or you hate'em)

All good

Mike

[alpal]

Originally Posted by strongmanmike

Thanks for that Allan, had seen that article before but never put it into practise...must have a go on one of my uncalibrated images

Mike

Hi Mike,
it's one of the greatest processing tricks I've ever seen.
Notice how he doesn't lose that faint galaxy?
The mouse over on the final picture is amazing.

cheers
Allan

[prokyon (Werner Probst)]

Great work, Mike! You captured so many faint details. And I like the colors.

Cheers

Werner

[SkyViking (Rolf)]

Originally Posted by alpal

Hi Mike,
it's one of the greatest processing tricks I've ever seen.
Notice how he doesn't lose that faint galaxy?
The mouse over on the final picture is amazing.

cheers
Allan

Ouch, that seems a bit too Photoshopped for my taste
There is certainly an improvement to the image, but as he states on the page it is really a "last gasp effort". I think replacing 99% of the image with a subjective artificial background, complete with fake noise, is pretty much in the same category as selective brightening and lassoing etc.

[alpal]

Originally Posted by SkyViking

Ouch, that seems a bit too Photoshopped for my taste
There is certainly an improvement to the image, but as he states on the page it is really a "last gasp effort". I think replacing 99% of the image with a subjective artificial background, complete with fake noise, is pretty much in the same category as selective brightening and lassoing etc.

99% - I don't think so - he's replacing false lumpy looking noise with
a more perfect even noise without losing the faint details of that galaxy.