NGC5139 Omega Centauri

[Paul Haese]

I only got a few short subs on this object during the weekend. It could do with a lot more data; perhaps double what this image has. I am very happy with the resolution and the how the core looks. There is a pesky satellite trail in the image, which is part of my luminence. More data will mean eliminating that problem.

Let me know what you think if you like.

Click here (http://paulhaese.net/NGC5139TSAQSI.html)for image.

[DavidTrap]

Very nice Paul.

What were your sub durations?

DT

[Paul Haese]

Thanks David. The subs were 5 minutes each.

[wysiwyg]

Really like this one Paul, its a very interesting object, one I hope to get around doing myself soon :)

[h0ughy]

nice image Paul - like the detail you have obtained

[Ross G]

Nice photo Paul.

So many stars and so much colour.


Ross.

[Sarge]

Good one Paul. Colourful with clear detail and depth. 5139 is certainly photogenic. :2thumbs:

Rod
:D:D

[multiweb]

Yes - beautiful field indeed. :thumbsup:

[CoolhandJo]

Nice contrasts. :)

[DavidTrap]

Very impressed that you maintained such core detail with 5min subs - were you using the high or low gain setting on the QSI? (just trying to workout how to achieve a similar result myself!)

Ta
DT

[Paul Haese]

High gain David. Very dark skies there though and quite still on the night. Seeing was around 7/10 on that night. Using CCDstack prevents burn out with the first thing I do is the DDP and autoscale inadjust display. Then later in PS I use shadows and highlights, focusing on preventing burn out and bringing up the stars in the outer field too.

Also, don't forget this is an 102 TSA, not a lot of diameter to work with really and longer subs are needed. Although 47 Tuc only needs 2 minutes each sub and then some 15 second subs to mask out the blown core (need to do this oject again this year to sort my previous image).

[peter_4059]

Lovely image Paul. What software are you using for DDP?

[desler]

You've done very well there Paul. Great colours, so many stars, a pleasure!

Darren

[Paul Haese]

Thanks guys.

Peter I use CCDstack for DDP.

[Tom Davis]

Big beautiful ball of stars!!

-Tom

[strongmanmike]

Ah good'l OC gotta love her :thumbsup:

It could be my work moniter or maybe just the image scale/FOV...but the only little thing I'd comment on is that it looks more like 47 Tuc :shrug:, the outer araes look a bit flat and the core a little round and concentrated. Omega is generally more bulbous and oblate, I imagine your stretching and shadow highlights may have caused this?

Looks good still :)

Mike

[Paul Haese]

Yes I had the exact same thought Mike. Omega is supposed to have a bulgy look to it. Maybe a curves function might restore the balance a little?? I will have a play ans see what transpires.

[gregbradley]

Nice shot Paul. The TSA frames it very well and is such a sharp scope so that is great. Tracking is fabulous. I agree though with Mike.

I used to use Shadows/Highlights a lot but now I am very careful with using it. Its a handy tool but like the minimum filter and the unsharp mask it is quite limited and best used inverted masked so it can be toned down afterwards. It can easily "flatten" an image so it loses its varying dynamic range. Too much selective colour can do a similar thing. The much brighter core is what this object looks like.

But that is a really minor point in an overall excellent image. A bit more exposure would give the colours more depth.

In a way we consider Omega Centauri an "easy target" but really it is quite a handful to take it to that exceptional level. I haven't captured to a level I am happy with yet.

Your image is better than the recent NASA APOD of the same object though (not that that would be hard).

Greg.

[Paul Haese]

Thanks Greg, certainly agree that shadows and highlights has to be used carefully. Even when I think it is just right it can be still slightly wrong. I have just done a small tweek to the image and that seems better but I suspect I will need to gather more data tonight and then do a nice reprocess.

Although it is easier to process than 47 Tuc, I agree getting it right can be a little tricky.

[DavidTrap]

Thanks for that Paul. Obviously I've got a similar setup to yourself, albeit a doublet - so I'm keen to try for something similar.

Hopefully some of the mysteries of processing will be revealed by the upcoming conference!

ta
DT

[gregbradley]

Yeah that tweak makes all the difference. Very nice.

They look better usually with medium focal length although the smaller globs of course require longer focal length.

They aren't necessarily an 8 hour image. The best are often quite short in total exposure and short sub exposures. You don't want a weak washed out look either from lack of exposure time - so there is a judgement point there. A 5 hour Omega Centauri probably would not look any better than a 45 minute one. You could possibly do some short and some long and do an M42 style composite.

Star colours need to be really brought out. Daniel Verschase was the master of that. His globs set the standard nobody has bettered yet. He seemed to get golden stars in his that look fabulous. I think he used selective colour a lot to achieve that.

Greg.

[stevous67]

Yep, like yours much better Paul:

http://apod.nasa.gov/apod/image/1003/ngc5139_100319lehman.jpg

Steve