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  #21  
Old 02-03-2009, 04:09 PM
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spectacular shot!
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  #22  
Old 02-03-2009, 05:50 PM
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Great work Tom. The crop is a real cracker. Thanks for sharing.
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  #23  
Old 02-03-2009, 08:26 PM
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Great image Tom! I just spent a few minutes staring at the image looking around at everything. Well done keep them coming..

Troy
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  #24  
Old 02-03-2009, 08:43 PM
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Quote:
Originally Posted by Tom Davis View Post
Hi Greg,

The dust is real but very very faint. I brought it out with curves but only made it stand out with the mouse-over. I am surprised that dust was in the region as well. Maybe it is flux nebulosity. I'll have to check.

Tom
First of all a spectacular image Tom

It seems now that an image is not truly deep if there isn't "Galactic Cirrus" or other faint dust showing (You should know Mr Dust Pan ). Funny how things progress in any endeavour or sport etc. Another good example is the Dumbell Nebula, if the outer radial Ha sprays aren't showing then it just ain't deep enough, 20yrs ago amateurs didn't even know that nebulosity was there . In a talk he gave to the Ice in Space Astro Camp back in 2007, David Malin issued a challenge to see if an amateur could reveal the very faint GC around Cen A and this was what propmpted my efforts to capture it but I am sure this nebulosity will soon be commonly seen in images of Cen A before too long.

It is very interesting to compare your relative marathon (for a globular image) to my almost snap shot - at first there appears to be little difference in size but once you reference some outliers in both images the extent you have revealed is quite large.

Yep as mentioned, that dust is more commonly known as Galactic Cirrus and has been for many years in fact. David Malin imaged heaps of GC a generation ago. "Integrated Flux" is a term more recently coined by some people who claim they were the first to showcase it as a mixture of emission and reflection, so the term seems to have stuck, particularly in the US.

Here is Our own Steve Crouchs effort from 2006 showing some GC near Omega Cen note the short exposure times...F2.8 helped of course:
http://members.pcug.org.au/~stevec/N...TL11K_E180.htm
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  #25  
Old 02-03-2009, 09:06 PM
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Originally Posted by strongmanmike View Post
First of all a spectacular image Tom

It seems now that an image is not truly deep if there isn't "Galactic Cirrus" or other faint dust showing (You should know Mr Dust Pan ). Funny how things progress in any endeavour or sport etc. Another good example is the Dumbell Nebula, if the outer radial Ha sprays aren't showing then it just ain't deep enough, 20yrs ago amateurs didn't even know that nebulosity was there . In a talk he gave to the Ice in Space Astro Camp back in 2007, David Malin issued a challenge to see if an amateur could reveal the very faint GC around Cen A and this was what propmpted my efforts to capture it but I am sure this nebulosity will soon be commonly seen in images of Cen A before too long.

It is very interesting to compare your relative marathon (for a globular image) to my almost snap shot - at first there appears to be little difference in size but once you reference some outliers in both images the extent you have revealed is quite large.

Yep as mentioned, that dust is more commonly known as Galactic Cirrus and has been for many years in fact. David Malin imaged heaps of GC a generation ago. "Integrated Flux" is a term more recently coined by some people who claim they were the first to showcase it as a mixture of emission and reflection, so the term seems to have stuck, particularly in the US.

Here is Our own Steve Crouchs effort from 2006 showing some GC near Omega Cen note the short exposure times...F2.8 helped of course:
http://members.pcug.org.au/~stevec/N...TL11K_E180.htm
Hi Mike is there a link to your Cent A image?
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  #26  
Old 02-03-2009, 09:17 PM
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Hi Mike is there a link to your Cent A image?
Your kidding right..? I'll be lynched if I post a link to another Cen A


...?...ok...carefully looking out fropm under the blankets...

http://www.pbase.com/strongmanmike20...61387/original

and here is a mozaic of three different results from the same data set:

http://www.pbase.com/strongmanmike20...43142/original

ah what the heck... here is the whole bleedin album

http://www.pbase.com/strongmanmike2002/centaurus_a

I'm running for cover now

Mike
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  #27  
Old 02-03-2009, 09:32 PM
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Brilliant you can come out now
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  #28  
Old 03-03-2009, 01:49 AM
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Quote:
Originally Posted by strongmanmike View Post
Here is Our own Steve Crouchs effort from 2006 showing some GC near Omega Cen note the short exposure times...F2.8 helped of course:
http://members.pcug.org.au/~stevec/N...TL11K_E180.htm
Yep, it's there. Great to know!

Thanks Mike!

Tom
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  #29  
Old 03-03-2009, 01:57 AM
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Tom, as I asked in an earlyer post, is that green dot at six oclock position an artifact?
cheers
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  #30  
Old 03-03-2009, 03:32 AM
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Tom, as I asked in an earlyer post, is that green dot at six oclock position an artifact?
cheers
I can't see it. Can you point it out on my image and I'll look at the full frame to let you know what it is.

Tom
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  #31  
Old 03-03-2009, 09:25 AM
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I can't see it. Can you point it out on my image and I'll look at the full frame to let you know what it is.

Tom
Thanks Tom
Sorry to desecrate your imagebut here goes
It is on both the cropped and uncropped images
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Click for full-size image (Omega Cent green dot.JPG)
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  #32  
Old 03-03-2009, 11:37 AM
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Originally Posted by astroron View Post
Thanks Tom
Sorry to desecrate your imagebut here goes
It is on both the cropped and uncropped images
I don't know. It looks like an star with very green bias. Strange though, as it is the only one. What do you think? I've seen a few small planetary nebulae that come off with a green bias but this is green! Great pick up!!

Tom
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  #33  
Old 03-03-2009, 03:57 PM
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That's just an artifact. You got a cosmic ray or hot pixel in your green sub that wasn't in the others. I often see blue dots in some of my images when I don't use median combine. Its just a bit of noise.

Greg.
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  #34  
Old 03-03-2009, 06:06 PM
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Greg, I wish you had seen the post and replied sooner, I sent an email to a professional Astronomer I know with the thread requesting any info on this possible P/N or very green star, and you had posted your reply as I was sending my messageunbeknown to me
I then got a reply agreeing with your post
I was surprised Tom didn't see it or know the reason for it being there.
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  #35  
Old 03-03-2009, 08:25 PM
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Quote:
Originally Posted by astroron View Post
Tom, as I asked in an earlyer post, is that green dot at six oclock position an artifact?
cheers
wow Ron how the hell did you spot that i still couldnt see it
even once you circled it and yes i still do have 20/20 vision
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  #36  
Old 03-03-2009, 08:59 PM
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wow Ron how the hell did you spot that i still couldnt see it
even once you circled it and yes i still do have 20/20 vision
Hi Jen, I get that asked quite a bit when I have people look through the scope It comes with doing lots of observing over twenty odd years, and being naturally a nosey Person

Last edited by astroron; 06-03-2009 at 11:11 PM. Reason: Spelling
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  #37  
Old 04-03-2009, 01:23 AM
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Quote:
Originally Posted by astroron View Post
Greg, I wish you had seen the post and replied sooner, I sent an email to a professional Astronomer I know with the thread requesting any info on this possible P/N or very green star, and you had posted your reply as I was sending my messageunbeknown to me
I then got a reply agreeing with your post
I was surprised Tom didn't see it or know the reason for it being there.
I don't think it is a cosmic ray hit. I downloaded off the internet different versions of Omega Centauri taken by other other imagers. After aligning them in Registar my "green star" aligns perfectly with a star in their image. It is not a cosmic ray hit or it would be much more random in location and shape. That said, I do think that is it likely to be just an artifact of processing. Hot pixel likely overlying the star I'd bet. Median combine was used.

Tom
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  #38  
Old 04-03-2009, 08:10 AM
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Hi Tom,

Yes cosmic rays are more like a little squiggle/worm. By the way I notice there are way more cosmic rays picked up by the 16803 chip. I was surprised when I saw how many there were in my darks. Requires lots of darks to get them out.

I often wonder why some of my images have little green, blue or red dots and others have virtually none.

Perhaps a mismatch of darks and lights somehow?

I notice it happens more if I use say sum combine which is handy for galaxies as it brings slightly more detail out but it leaves the artifacts in.

I often scout around at high zoom in looking for any stray red green or blue dots and healing brush them out. Sometimes there are none, other times there are quite a few. Perhaps slight processing routine changes account for that. Also I have had it that say an asteroid has been in the shot but that is 3 red green blue dots in a straight line slightly apart as it moved whilst being imaged with the 3 different exposures for each filter.


Greg.
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  #39  
Old 06-03-2009, 10:42 PM
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Hi Jen, I get that asked quite a bit when I have people look through the scope It comes with doing lots of observing over twenty odd years, and being naturally a nosy Person
well there is nothing wrong with your eye site
so dont look at my pics then when i FINALLY get to post one of these days
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  #40  
Old 06-03-2009, 11:11 PM
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Wonderful image Tom, very stunning.

Cheers
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