Centaurus A 27 Hours extreme repro!

gregbradley · #1 07-07-2012, 10:45 AM

I have done a repro of this one to address some of the critiqued points. Stars rounded, faint perimeter of the galaxy pushed hard.
Its now rather a unique view.

I took this image over several weeks and 4 or 5 hours a night.

Again, there were some periods of good seeing during the imaging.

The points of interest in this image are apart from the new stars in the blue/pinkish regions but there is a blue jet at about 8 oclock. I first noticed this on an image I took of Cent A with my TEC180 from my dark site.

I also am interested in this image as it shows the dust band which crosses Cent A also extends a large way under the ellipitical galaxy itself. So vast amounts of dust have been spewed under the galaxy from this merge. I haven't noticed this spread of dust in other images and seems to be the advantage you get from 27 hours!

Planewave CDK 17, Proline 16803, STi and Lodestar guiders, Paramount PME mount in my home observatory. Luminance exposures were typically 15 minutes, RGB 2x2 and 10 minutes although I did several hours of RGB 1x1.

I think for galaxies in future I will shoot RGB 1x1 and 10 or 15 minutes to get maximum little details and resolution.

This is an extreme version of the image maxed out to show extent of the galaxy:

http://www.pbase.com/gregbradley/image/143890305/large

Greg.

Peter Ward · #2 07-07-2012, 11:29 AM

Humm... deep for sure, but sorry Greg the stars are and odd shape and the colour looks very flat...almost posterised on my monitor.

Something's not quite right in either the stacking or optical alignment or both is my guess.

But kudos for such a heroic deep field effort.

alpal · #3 07-07-2012, 12:55 PM

Hi Greg,
Is this the photo from Mike that you refer to?

http://www.pbase.com/strongmanmike2002/image/97061387

Mike somehow captured more of the faint nebulosity of
the background as well as the galaxy.
You still have more resolution in the dust lanes.
I think you have a great picture but you may want
to have another go at re-processing it.
The problem is that when you have a 17" Planewave people expect a lot more -
maybe too much as the seeing conditions are the real limitation.

I only wish I had your kind of data to play with.

cheers
Allan

allan gould · #4 07-07-2012, 01:25 PM

Greg,
27 hours for an image is totally heroic but I understand why when you are trying to get that faint detail that N5128 has in the background and it's outer shells. To me the colour looks great on my iPad and it's the sort that I want for my image but the clouds and rain are coming so it will be a while. From the suburbs of Brisbane I don't think I'll get that sort of colour saturation and subtleness especially with the moon at present.
But I'd love that scope of yours. Thanks for another great image.
Allan

gregbradley · #5 07-07-2012, 01:50 PM

Quote:

Originally Posted by Peter Ward

Humm... deep for sure, but sorry Greg the stars are and odd shape and the colour looks very flat...almost posterised on my monitor.

Something's not quite right in either the stacking or optical alignment or both is my guess.

But kudos for such a heroic deep field effort.

Thanks for the critique Peter.

Quote:

Originally Posted by alpal

Hi Greg,
Is this the photo from Mike that you refer to?

http://www.pbase.com/strongmanmike2002/image/97061387

Mike somehow captured more of the faint nebulosity of
the background as well as the galaxy.
You still have more resolution in the dust lanes.
I think you have a great picture but you may want
to have another go at re-processing it.
The problem is that when you have a 17" Planewave people expect a lot more -
maybe too much as the seeing conditions are the real limitation.

I only wish I had your kind of data to play with.

cheers
Allan

Yes that's the one.
To get that deep space halo will require ultra dark skies like I have at my dark site observatory. Unfortunately my CDK17 isn't a portable scope. It takes 2 people to mount it. Perhaps one time over the Christmas break when I would be there for a while it would be worth carting it down and setting it up. But in the meantime I have reasonably dark skies where I am and rely on gradient processing to get rid of most of the effects of the small amount of light pollution I get. My image is more about the dust lane and details that did come up well. The extended star halo may be a target for my APOs at my dark site. That extended halo isn't in the data to bring out as I looked for it. Seeing was variable during the imaging from some good nights to some average nights. That's a limitation we all face in imaging.
Like snow skiing, sometimes the snow isn't that great, other times its fabulous. Martin has shown how good the scope is on a remote mountain top with among world's best seeing. That's not my location though.

Quote:

Originally Posted by allan gould

Greg,
27 hours for an image is totally heroic but I understand why when you are trying to get that faint detail that N5128 has in the background and it's outer shells. To me the colour looks great on my iPad and it's the sort that I want for my image but the clouds and rain are coming so it will be a while. From the suburbs of Brisbane I don't think I'll get that sort of colour saturation and subtleness especially with the moon at present.
But I'd love that scope of yours. Thanks for another great image.
Allan

Cheers Allan. I liked the level of detail that came out.

Greg.

gregbradley · #6 07-07-2012, 03:03 PM

I've done a repro and addressed the critiqued points. I corrected some slight elongation on outer stars (a bit of flex I think), the colours and pushed the data. There was more data than I originally thought but then you would expect that given its 27 hours at F6.8.

A pretty wild object.

Same link as original post:

http://www.pbase.com/gregbradley/image/143890305/large

Greg.

Peter Ward · #7 07-07-2012, 03:08 PM

Quote:

Originally Posted by gregbradley

I've done a repro and addressed the critiqued points. I corrected some slight elongation on outer stars (a bit of flex I think), the colours and pushed the data. There was more data than I originally thought but then you would expect that given its 27 hours at F6.8.

A pretty wild object.

Same link as original post:

http://www.pbase.com/gregbradley/image/143890305/large

Greg.

Stars much better now!

Peter

alpal · #8 07-07-2012, 04:30 PM

That's better now - there is plenty of background detail showing through.

Where has the large full FOV pic gone?

gregbradley · #9 07-07-2012, 05:29 PM

Quote:

Originally Posted by alpal

That's better now - there is plenty of background detail showing through.

Where has the large full FOV pic gone?

Thanks.
This is the wide field of view image. There is no crop on this. Its just pushed a lot more.

Greg.

Paul Haese · #10 07-07-2012, 05:44 PM

Smooth background and round stars. However, for me this image looks flat in the full size image. The dust lane lacks definition in my opinion and it does not look as sharp as it could with selective sharpening applied. Not doing it for me Greg. Sorry.

Ross G · #11 07-07-2012, 06:09 PM

Great photo Greg.

You have acheived what you set out to do, show the extent of the galaxy.
It is an amazing and unique view of a common object...looks like a cross.

Thanks.

Ross.

atalas · #12 07-07-2012, 06:40 PM

Extreme!different,I like It a lot! very nice Greg.

gregbradley · #13 07-07-2012, 07:26 PM

Quote:

Originally Posted by Ross G

Great photo Greg.

You have acheived what you set out to do, show the extent of the galaxy.
It is an amazing and unique view of a common object...looks like a cross.

Thanks.

Ross.

Cheers Ross.

Quote:

Originally Posted by Paul Haese

Smooth background and round stars. However, for me this image looks flat in the full size image. The dust lane lacks definition in my opinion and it does not look as sharp as it could with selective sharpening applied. Not doing it for me Greg. Sorry.

I've sharpened it a tad more and made the colour more vibrant. I think its at the end of any gains available with that data set. Thanks Paul.

Quote:

Originally Posted by atalas

Extreme!different,I like It a lot! very nice Greg.

Cheers Louie. Its turned out pretty wild.

Greg.

alpal · #14 07-07-2012, 07:41 PM

Quote:

Thanks.
This is the wide field of view image. There is no crop on this. Its just pushed a lot more.

Greg.

Sorry - I meant the original version, here:
http://www.pbase.com/gregbradley/ima...90305/original

Anyway - I found it.

Quote:

The points of interest in this image are apart from the new stars in the blue/pinkish regions but there is a blue jet at about 8 oclock.
I first noticed this on an image I took of Cent A with my TEC180 from my dark site.

Yes - I like the way you've picked up some of the red
regions on the dust lanes & also that jet -
just as in the famous ESO pic:
http://www.solstation.com/x-objects/cent3new.jpg

gregbradley · #15 07-07-2012, 08:52 PM

Quote:

Originally Posted by alpal

Sorry - I meant the original version, here:
http://www.pbase.com/gregbradley/ima...90305/original

Anyway - I found it.

Oh I see, yes you click on "original" at the bottom of the image to get the larger size.

Yes - I like the way you've picked up some of the red
regions on the dust lanes & also that jet -
just as in the famous ESO pic:
http://www.solstation.com/x-objects/cent3new.jpg

That's an interesting image. It did not pick up the extent of the dust but it has picked up a 2nd outer part of that jet that I do not see any hint of in my image.

Thanks for the link.

Greg.