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Fornax A

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#1 Asbytec

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Posted 28 December 2019 - 10:36 PM

After two late season tropical storms, I decided to revisit NGC 1365 to spot those darn spiral arms. I failed. However, looking at Sky Safari, I noticed another interesting galaxy nearby. A quick star hop and I was in for a surprise. I have never seen Fornax A.

 

But, my gosh! It was very bright and showed some detail almost immediately. The NE SW elongation was immediately visible with a faint glow. Almost right away I began to see hints of some dark lanes, first and most prominent to the west. Later and less prominent to the east. Then, I noticed NGC 1317 further out in the FOV. I was kind of shocked as it appeared to be faint, but pretty large compared to the NGC 1316. It had a small but distinct elongated core, too.

 

Edit: what I am not sure of is whether those dark lanes are the edge of the halo or the finer dark stuff near the core. I might be pushing it thinking they are the dark lanes near the core, so they are probably the more dark edge to the halo. I did not see any of the more extravagant (and faint) halo structure. (I actually have the same question about the dark stuff I noticed in NGC 1365).

 

It was best seen at 150x (1.3mm exit pupil). I did not get to stay on it for much longer than 30 minutes due to a huge cloud bank rolling in. Had a descent night otherwise, clear and fairly transparent. But, that was enough.

 

Fornax A.png


Edited by Asbytec, 28 December 2019 - 10:39 PM.

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#2 Raul Leon

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Posted 28 December 2019 - 10:54 PM

Hi Norme,

                    Interesting observation, I have not seen this object for quite awhile and have it on my list now for a revisit. Thanks for sharing and reminding me .


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#3 frank5817

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Posted 28 December 2019 - 11:04 PM

Norme,

 

A very good looking sketch of these galaxies.

 

Frank :)


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#4 Asbytec

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Posted 29 December 2019 - 02:11 AM

Thank you both, This galaxy is a real treat. 

 

Two things kind of shocked me. First, I was shocked how big NGC 1317 was compared to the visible parts of NGC 1316. I may not have drawn it quite to scale. Probably should have drawn it a little larger. Second, in images NGC 1317 is tucked in close to NGC 1316, but I was surprised to find it a bit further away. This just means I was not seeing the dimmest halo of NGC 1316 which must be quite large. But, if I did not see the dim halo, then I may not have seen the abrupt edge to it as I thought and tried to illustrate (it really wan't an "edge" anyway, more or less embedded). I am wondering if those dark lanes are the higher contrast one's in closer to the core. Maybe. The western dust feature is more prominent, and that is consistent with what I noted. But, if so, I do not remember seeing any of the dust trailing toward the core. 

 

In the image below, though the core is over exposed, if you look at it just right, the dark lanes look about right. That's a pretty nice visual impression. 

http://www.rochester...006/n1316s7.jpg

 

And I am not the only one:

https://www.cloudyni...rt-1/?p=7587955

https://www.cloudyni...316-dunlop-548/

 

I need to revisit NGC 1365 again. Same question. 


Edited by Asbytec, 29 December 2019 - 02:18 AM.


#5 GUS.K

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Posted 29 December 2019 - 05:14 AM

Great sketch Norme, thanks for sharing.


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#6 niteskystargazer

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Posted 29 December 2019 - 11:16 AM

Norme,

 

Very good sketch of Fornax A smile.gif .

 

CS,KLU,

 

thanx.gif ,

 

Tom


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#7 astronz59

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Posted 29 December 2019 - 03:54 PM

Beautiful rendering of these two, Norme! How do you get your stars so round? I always struggle with this while sketching at the telescope. waytogo.gif



#8 IVM

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Posted 29 December 2019 - 06:50 PM

Great view. I viewed this field just last week at culmination about 10 degrees above the horizon. Seems to be an object I missed when observing from the Southern Hemisphere. Similarly I wasn't certain if I saw any of the dust near the center in the 20-inch, but I think it was a smaller dark feature closer to the nucleus that I was going for. Didn't make a sketch - too low.


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#9 Asbytec

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Posted 29 December 2019 - 06:55 PM

Beautiful rendering of these two, Norme! How do you get your stars so round? I always struggle with this while sketching at the telescope. waytogo.gif

Thank you. I revisited Fornax A last night and, to my horror, realized I sketched it too big. I was at various magnifications and, for some reason, I seem to remember it as being big. Visually, it was about half that size or less. Oh well, just gonna leave it as is. 

 

I sketch from my notes using GIMP. It has different brushes you can use to make stars pretty much round and pixelated with a high zoom. For faint stars, you can fill one pixel, but they are tiny. So, then you can fill some adjacent pixels to give it a better appearance. If a star does not look right, sometimes I'll fiddle with the pixels. Bright stars are usually larger covering many pixels. 



#10 Achernar

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Posted 03 January 2020 - 09:12 AM

Great sketch of these galaxies. I have observed, and sketched them from Alabama in fact.

 

Taras



#11 Asbytec

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Posted 03 January 2020 - 09:18 AM

Great sketch of these galaxies. I have observed, and sketched them from Alabama in fact.

Taras


I'd love to see your sketch, Taras. I'm using the CN app and cannot see your signature. Ill have to log on later. If possible, please post a link to your site and sketch. Thank you for commenting.

#12 Asbytec

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Posted 10 January 2020 - 03:11 AM

Great view. I viewed this field just last week at culmination about 10 degrees above the horizon. Seems to be an object I missed when observing from the Southern Hemisphere. Similarly I wasn't certain if I saw any of the dust near the center in the 20-inch, but I think it was a smaller dark feature closer to the nucleus that I was going for. Didn't make a sketch - too low.

Sorry I missed your reply. I dunno, a 20" is plenty powerful aperture. Low altitude might be enough to make detail that much more difficult in any aperture. I cannot say for sure. I cannot avoid the vision of something being there. Not clearly seen, but often hinted at or glimpsed (maybe). Believe me, I held no hope of seeing anything so exotic as those dust features near the core. I thought I was seeing the edge of the halo where some images show a bit of a sharp drop off. But, as it turns out, I do not think I was seeing as much of the dimmer halo that extends much closer to NGC 1317 or any of the very low contrast that would result form such a dim halo. About the best I can do it to see the brighter portions of the galaxy. So, I am left with only one option. 

 

I think I may have made the same mistake with NGC 1365, never hoping to see anything near it's fine dust features pinching into the core. Really, that's too much to ask of me and a modest 8" aperture, surely. Still, I cannot escape the fact something was teasing my eye (thus my brain) in the vicinity of the brighter bar. Again, some images show some sharp drop off of it's halo in about that same place, too. So, my first guess was a sharp drop off instead of a fine dust feature. Just seems the easier of the two features to see. 

 

Still, it's hard to use filtered and processed digital images to replicate the visual appearance. So, it's really hard to select one image over another that seems to describe what we are seeing. So, upon verification of some sightings, I kind of have to mix and match some images to get a feel for what might have been seen. And I do not mean actually seen so much as detecting something as being there. It's just not at all clearly defined, as I am sure we understand. Almost an artifact, but one that is somewhat consistent in its location. Something that is teasing us and we read the "behavior" of the image as it comes and goes. 

 

So, truthfully, I do not know which detail I actually got an impression of. Thinking about it, the higher contrast of a darker feature against a brighter core makes more sense than the very low contrast of a sharp edge to an invisibly dim halo. Maybe not. Maybe the latter is easier for some unknown reason. But something crept into the image letting me know something was trying to be seen. I really could not make it out other than to know somethign was there, and turns out there is something there. Question is, what was it? My imagination? 

 

Also, truthfully, I really didn't think much about the finer dust features, they were not on my mind. So, I do not believe I was trying to see something I didn't think I could see nor a detail I paid no mind to. I never know what to expect even if I know what the galaxy looks like. Something that seems easy in a digital image, sometimes is not even remotely visible. And visa versa. Sometimes things that look impossible or we have little expectation and hope of seeing it, sometimes we do. Just a weak undefined signal tickling our optical nerve and registering on the brain undefined and unseen...but, in a way, it is seen. Especially when some feature is there and may well have caused the impression we register in our mind. It's those difficult clues I pay attention to trying to read very faint signals. 

 

I paid attention to notoriously faint M74 for two hours each over two nights. I cannot say I ever saw the spiral arms in the way we say we see things. I did actually catch some dimming and one brighter knot in the faint fuzzy halo. But, even without seeing the arms, I knew where they were and which way they were oriented. I made notes, and upon verification (flipping and rotating a digital image to match my FOV and field stars, I had no preconceived idea of it's orientation) I was absolutely astonished I got it right. They were probably nothing more than a slight variation in the background noise and somehow my brain picked up on it. Other than a soft darkening and a brighter knot, I have absolutely no visual recollection of having seen the spiral arms in the way we remember seeing things. Not even close to remembering a digital image we've seen. All I remember seeing is a faint fuzzy, a slight and fleeting dimming, and a rare glimpse of a brighter knot. That's my mental image. 

 

I understand the importance of seeing something and confirming it by actually seeing it. I've seen enough effects of some features on the image of a galaxy that I do not strive to see the feature itself to know it's there, rather to recognize the effect it has on the very dim image we do see and the weak signals we pick up on. Over time, I've learned to trust those weak, tantalizing, and nearly unseen effects. And I try to understand that, often enough, there is something present just below our perception of it to cause an effect we can barely detect as a very vague something in the image. Fleeting. Glimpsed. All those words apply. We just have to learn to trust them and ourselves. And, of course, verify. :) 


Edited by Asbytec, 10 January 2020 - 03:25 AM.

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