NGC1365, NGC1097, NGC1566 from last night

[peter_4059]

I set the 10" up last night with the intention of getting some images of Saturn and decided to fill the time before Saturn appeared by imaging some interesting galaxies. Being so close to Brisbane there was quite a bit of sky glow to deal with but I'm quite happy with the results.

Unfortunately when Saturn finally appeared so did the clouds and judging by the weather forecast it looks like it will be the new year before I'm going to get another try.

All images are 50x1 min subs using the 10" Newt guided on the EQ6 and the DSI II pro.

As always there's still a lot to learn - comments welcome. Thanks for looking (and for the company Allan).

[AlexN]

Great set of galaxies Peter..

I've still not captured a galaxy yet (M31 is too big to count as a galaxy... its like capturing a house with a 50mm camera lens... Not hard :D

Those look great to me... perhaps a bit dim, but otherwise fantastic.

[AlexN]

I hope you dont mind my doing so, but I had a quick play with 1365 in photoshop.. stretched it a little more, maximum entropy deconvolution (very low settings) and a tiny touch of noise reduction..

I dont know if its "Better" but its easier to see the detail in it now!

Alex

Edit : hit it with gradientXterminator too... uploaded again...

[multiweb]

Three truly awesome pictures Peter. Lots of details. Love'em. Top work. :thumbsup:

[Martin Pugh]

Hi Peter

good work. I can tell focus was spot on as you have resolved some great detail there. I also agree that they are a little dim. In Photoshop, duplicate the background layer and in that second copy, make a selection around the core of the galaxy, and feather it by 15 pixels or so. Select 'Inverse'. Now add a curves adjustment layer. Click ok without making any adjustments. Then right click on the curves adjustment layer and select 'Create Clipping Mask'. Now,click on the curves icon in the adjustment layer and make your adjustments carefully. You will bring up the brightness of the outer arms and background without burning out the core of the galaxy.

Now, merge down the curves adjustment layer with the background copy layer, and adjust opacity of that layer to get just the right finish. Now flatten.

HTH

Cheer
Martin

[peter_4059]

Thanks for the comments and suggestions Alex, Marc and Martin. I tried the routine you suggested Martin (after finally working out the correct section of the curves adjustment layer to right click on to make 'Create Clipping Mask' appear) however I'm finding the background (gradient) becomes very prominent. Is there a way to remove this without GradientXterminator?

[AlexN]

raising the black point in levels can remove the gradient, but at the cost of also losing some of the fainter areas in the outer arms of the galaxies..

You could try selecting the galaxy, expand and feather the selection and then brighten the galaxy... Then, invert the selection and raise the black point for the background sky...

I've never tried this, but in theory, it should achieve what you are looking for.

[multiweb]

There are a number of techniques to remove gradients if you google around. If it's a color gradient the imbalance can be corrected directly within the color channel.

[renormalised]

Great work, Peter:D

It's sobering to think that little dot of light that's NGC 1365 is actually about 63Kpc across!!. Pretty big when you think about it:D.

[Alchemy]

some nice galaxies there :thumbsup:

clive

[peter_4059]

Interesting point - I checked out the distances and they are all similar (give or take 10 million ly's.

NGC1365 65 million ly (extends 200,000 ly)
NGC1097 53 million ly
NGC1566 51 million ly

I selected these based on an astroplanner search sorted by angular size and magnitude. Judging by the image scale in the pictures I guess that means they are all similar in actual size?

[Garyh]

Very nice and crisp images Peter!
:thumbsup:

[renormalised]

To better measure the actual size of the galaxies, given their angular size, just use the small angle formula and plug the variables into the equation. That way, you'll get a better approximation of their size, rather than relying on the image scale, which is normally deceptive.

[Ric]

You've captured some lovely galaxies Peter.

Fine work indeed.

[peter_4059]

Googled the small angle formula and calculated the sizes:

NGC1365 185,000 ly
NGC1097 143,000 ly
NGC1566 113,000 ly

Thanks for the tip.

[jase]

Excellent panel of galaxy images Peter. Sure they look a little unstretched, but all the qualities are there with good detail on display. Thanks for sharing.

[peter_4059]

Cheers Jase - not sure how to stretch much more without the background skyglow and noise becomming prominent. I've spent a number of hours playing with ps but still a lot to learn - any ps tips much appreciated.

[rogerg]

Nice galaxies, good to see what the DSI II can do on galaxies in 1min :thumbsup:

[renormalised]

Sure, no problem. Happy to help:D

[allan gould]

Merry Xmas Peter - three lovely shots and I like how you have held the detail in them. Love to see them whem you have had a go at processing them further

[peter_4059]

Cheers Roger - the DSI has been a great camera to learn with and is still keeping me interested more than a year later.

Allan - you'll never guess what I've been making today - almost finished cutting - no more mucking around with focus on the 10" :D

[peter_4059]

I've spent the last two days working through the book Photoshop Astronomy trying noise and gradient reduction techniques - here's my latest re-process of NGC1365. I think it's an improvement on my earlier processing attempt as I've managed to increase the brightness of the galaxy while reducing background noise. I've included the original attempt for comparison.

Comments and tips welcome!

[AlexN]

Fantastic improvement Peter!

Photoshop Astronomy has to be one of best books available to us astrophotographers..

Well done mate.. A top job indeed.

[allan gould]

Great improvement Peter - it was obvious the data was there, just needed to bring it out. Must ask how it was done

[gregbradley]

A great improvement.

Greg.

[atalas]

Three great shots with great detail ! congrats.