Wrongly rendered colliding galaxies

[t00fri]

Andrea,

Was an attempt to inject some levity into an otherwise seemingly hostile exchange of ideas.

Sorry, Bob, while I agree on most of what you usually say, this time I don't.
There is nothing hostile between me and Fridger (and I'm sure this is the same for Fridger).

Here I completely agree.

It's only been a strong opinions exchange of people that was sure of their ones, and that produced some positive results, i.e.:
1- the acknowledgement that some official scientific data are not sufficiently exact to give a real image of what's shown in (some? many? ALL?) colliding galaxies images, hense the impossibility to obtain with Celestia a real and scientific visualization of galaxy couples or triplets using such data;

Here I definitely disagree!

I have demonstrated with the example of the pair NGC 6050A,B that the substantially different distances in deepsky.dsc must be about correct. They have led to virtually perfect displays of that pair. We have also confirmed my original statement that it is VERY dangerous to infer from seemingly close-by galaxies that they are really close in space, unless there are conspicuous signatures of gravitational shape distortions!

All other examples I have examined earlier in this thread gave displays in stunning agreement with the Hubble photographs, of course, with exception of ANY gravitational shape deformations.

I really don't see, why you now conclude the opposite after this long discussion???

2- the understanding that even some official sources (e.g. NASA), that should give “only” information well supported by confirmed data, sometimes can give misleading information instead:

I completely agree.

For me this was not new, but rather confirmed previous experience...I have explained above why this is often so.

3- my personal understanding (yahoooo!) of how to obtain the wonderful galaxy images seen in Fridger's posts, that I had never been able to obtain before this thread.[/b]
I’m very satisfied of this, and I hope that all this may be of some help and interest for many other people apart from the two "contenders".

Excellent.


Cheers,
Fridger

[ANDREA]

There is nothing hostile between me and Fridger (and I'm sure this is the same for Fridger).

Here I completely agree.

I was sure of this, thank you.

[color=#000080]1- the acknowledgement that some official scientific data are not sufficiently exact to give a real image of what's shown in (some? many? ALL?) colliding galaxies images, hence the impossibility to obtain with Celestia a real and scientific visualization of galaxy couples or triplets using such data;

Here I definitely disagree!
I have demonstrated with the example of the pair NGC 6050A,B that the substantially different distances in deepsky.dsc must be about correct. They have led to virtually perfect displays of that pair. We have also confirmed my original statement that it is VERY dangerous to infer from seemingly close-by galaxies that they are really close in space, unless there are conspicuous signatures of gravitational shape distortions!
All other examples I have examined earlier in this thread gave displays in stunning agreement with the Hubble photographs, of course, with exception of ANY gravitational shape deformations.
I really don't see, why you now conclude the opposite after this long discussion???

Sorry Fridger, I was not clear, hell to my poor English!
First of all please remember that when I say "a real image of what's shown in (some? many? ALL?) colliding galaxies images" , I mean it in 3D, not 2D as you do, and this may be the difference between our approaches to this subject.
As I told I need for my lessons to go "around" those objects, to show how they were colliding (if they were really doing so, obviously!).
Speaking of 6050A,B only, I was only meaning that to obtain your perfect image match with Hubble's image you had to modify the 5050A distance data, as you said...

1) I take the accurate NED distance of 6050B for granted:
d(6050B) = 4.918e+08 ly (deepsky.dsc)
2) I assume the sizes from the catalogs are both correct
3) I then examined via Celestia and the Hubble images by how much I must make d(6050A) shorter than d(6050B) in order to match the size and distance relations apparent on the Hubble image.
Result: The distance d(6050A) turns out to be surprisingly well determined. Certainly it MUST be considerably smaller than d(6050B)! I find d(6050A) ~ 2.5e+08 ly while my uncertain method (deepsky.dsc) gave d(6050A) = 1.938e+08 ly. Not too far off, indeed...

...otherwise the deepsky.dsc data would not have given that perfect match between Celestia and Hubble image.
In my opinion, normally speaking, a 29% difference in price, height, speed or, as in this case, "distance" (1.938 ly versus 2.5 ly) was not so negligible.
Nevertheless, if this delta is within scientifically acceptable limits, you are obviously right, it's negligible.
But even after this scientific solution to the 2D viewing problem, I was saying that some (or only this one, perhaps) “official“ scientific data (i.e. NASA, when states 6050A,B as “colliding galaxies”), may be wrong, because they are NOT colliding: as you pointed out there are no gravitational distortions signs, as should be if they were truly colliding or even close to do it.
Nothing more.
So I think I didn’t say things so contrary to what you was saying, or not?

2- the understanding that even some official sources (e.g. NASA), that should give “only” information well supported by confirmed data, sometimes can give misleading information instead:

I completely agree. For me this was not new, but rather confirmed previous experience...I have explained above why this is often so.

Well, for me it has been a very negative surprise, I was ready to bet my house to one Euro that NASA could not be wrong!
Fortunately no one was betting with me!
Bye

Andrea