List of galactic clusters and voids

[Cham]

NOPE. You effectively used those box shapes to miscredit my deepsky.dsc data base in PUBLIC as totally unreliable

What are you talking about !? This has nothing to do with the critic I was doing on your distribution. Even without the blue boxes, we can clearly see the artifacts (RADIAL LINES). The galactic distribution is unreliable, as seen in 3D, with or without the cluster boxes. Of course, it's reliable as seen close to Earth, on the 2D celestial sphere. But NOT in 3D when the observer is standing very far away from the Milky Way.

And where did you found that I said "totally unreliable" ? I never said that.

As I said, the blue boxes were used to locate the clusters center, and nothing more.

[ElChristou]

Vince's script deserve almost a lua tool to be able to change values and display on the fly...

[t00fri]

NOPE. You effectively used those box shapes to miscredit my deepsky.dsc data base in PUBLIC as totally unreliable

What are you talking about !? This has nothing to do with the critic I was doing on your distribution. Even without the blue boxes, we can clearly see the artifacts (RADIAL LINES). The galactic distribution is unreliable, as seen in 3D, with or without the cluster boxes.

NOPE!
It is absolutely UNCLEAR at this point to which extent these radial lines are part of aproximations to REAL large scale filiaments and what part is artefact.

Certainly YOU do NOT know.

See my display of the filiaments in the virgo cluster above, which I think are REAL!

Of course, it's reliable as seen close to Earth, on the 2D celestial sphere. But NOT in 3D when the observer is standing very far away from the Milky Way.

That must be a joke. deepsky.dsc incorporates ALL knowledge about distances we have. Of course in physics there are always uncertainties. If you can do better distances or anybody else, tell me, please

And where did you found that I said "totally unreliable" ? I never said that.

You said THIS:

your galactic distribution looks like VERY unreliable

which is not much of a difference is it? ...

Fridger

[Cham]

And where did you found that I said "totally unreliable" ? I never said that.

You said THIS:

your galactic distribution looks like VERY unreliable

which is not much of a difference is it? ...

Now, you're really acting like a baby. Since when does "very" equals "totally" ? Come on, Fridger, you're smarter than this.

[Vincent]

Vince's script deserve almost a lua tool to be able to change values and display on the fly...

That can be done in celx, where we can use some keys to change the central value for RA and Dec.
We just set the dRa (= RAmax - RAmin) and dDec (= Decmax - Decmin) values in the script,
and then change the central values for RA and Dec using some keys...

[t00fri]

Anyway,

I will not be messing around with you further. I have really tried to give an objective account of possible sources of bias, on the previous pages. I am convinced there is not much one can do at this point to significantly improve such a 3d display. I think on the whole, it is certainly not bad at all. If we had a means of displaying uncertainties in Celestia there would be not the slightest evidence for inconsistency.

But all my above efforts were apparently just a vaste of my time.

Fridger

[Cham]

But all my above efforts were apparently just a vaste of my time.

So were mine, I guess.

Fridger,

I have another interpretation which may solve the issue. The radial lines which I'm seeing in Celestia may just be an apparent "skew", if the database is only containing a mix of discrete angular cut outs of the entire sky. If so, the database is (of course) showing only a small part of the real galaxies out there, in such a manner that apparent radial lines are emerging from the global distribution. This could simply be the result of the fusion of some discontinuous maps (or "surveys") on the celestial sphere. In other words : there could be some "selection effects" in Celestia's database.

Do you think this may be the case ? If so, we need to know, since the radial effect is so strong in Celestia (of course, I'm not talking about the "shadow" effect of our Milky Way). To me, this is so important that it may be worth to split the whole database into various catalogues (with some reference index).

Maybe a celx script which gives a different color to each catalogue could show this ?

[t00fri]

Well I just came across an independent confirmation of the straight streaks (constant RA,Dec) in distance that are evident in deepsky.dsc, from the FAMOUS Princeton conformal plot of the Universe!

The plot is from here
http://www.astro.princeton.edu/~mjuric/universe/
this is the famous original paper
http://www.astro.princeton.edu/~mjuric/universe/ms.pdf

I have cut out the lower part of this amazing display of ALL known data for RA vs. log(distance). It reaches up in distance where the large scale filiaments from Sloan SDSS, become very conspicuous. You notice the various galactic clusters like the Coma cluster.



+++++++++++++++++++++++++++
The crucial features I want you to focus on are these obvious straight vertical lines of galaxies (blue dots) for CONSTANT RA rising up in distance until they merge continuously into the more complex filiamentary structure of the SDSS data!!! This shows without doubt that these vertical streaks in distance for constant RA are there and that they are physical with high probability.
++++++++++++++++++++++++++

Here is once more the Celestia 3d plot, with the highly elongated Virgo I cluster emphasized in red. A ray in this plot corresponds of course just to CONSTANT RA like on the "conformal plot".


Fridger

[EDIT]: and YES there is a strong data selection bias notably at larger distances where the millions of galaxies from SDSS are lacking in my NGC/IC database of only 10000+ galaxies!

[Cham]

[EDIT]: and YES there is a strong data selection bias notably at larger distances where the millions of galaxies from SDSS are lacking in my NGC/IC database of only 10000+ galaxies!

Then why not making a celx script which marks all the galaxies with a different color, depending on the catalog they are coming from ? Maybe we could make the radial effect to disappear, if we look at each catalog seperately ? (and better see the bubbles and filaments...)

This could also explain the apparent discrepancy with all the clusters databases I tried.

[t00fri]

[EDIT]: and YES there is a strong data selection bias notably at larger distances where the millions of galaxies from SDSS are lacking in my NGC/IC database of only 10000+ galaxies!

Then why not making a celx script which marks all the galaxies with a different color, depending on the catalog they are coming from ? Maybe we could make the radial effect to disappear,

They are PHYSICAL. I don't want them to disappear. Why didn't you look at the Princeton plot!!?

if we look at each catalog seperately ? (and better see the bubbles and filaments...)

This could also explain the apparent discrepancy with all the clusters databases I tried.

You can do whatever you like.

I am convinced that my deepsky.dsc is as reliable as presently feasible and that most of the visible radial structures are the early (lower distance) manifestations of the large scale structure filiaments as conspicuous in the Sloan data.

++++++++++++++++++++++++++++++
From the independent "Princeton plot" above one can really trace the vertical lines of galaxies MERGING into the Sloan filiaments. So their physical nature is practically proven.
++++++++++++++++++++++++++++++

Fridger

[Cham]

You can do whatever you like.

Well, I'm not an expert in CELX coding, and you are the one who builded the database from several catalogs. So you're better placed to make that celx, isn't ?

[t00fri]

You can do whatever you like.

Well, I'm not an expert in CELX coding, and you are the one who builded the database from several catalogs. So you're better placed to make that celx, isn't ?

I will not loose any further time on this theme which was entirely "your invention"

What I might do at best is to print out my galaxies in exactly the same fashion as the Princeton plot above, RA vs log(distance). Then one can directly compare the two plots
as to the vertical lines of galaxies.

I really don't need more confirmation

Fridger

[Cham]

Then, maybe Selden's way is a better alternative to show the bubbles and walls, as a layer :

Selden_model.jpg

[t00fri]

Here comes a final point:

The uncertainties in the 2d (RA, Dec) coordinates of my 10000 galaxies are ABSOLUTELY negligible. So already from that fact it follows that the displayed galaxies must lie more or less on the rays that are seen, since any ray through the origin in that plot corresponds to a fixed value pair (RA,DEC)! Deviations of galaxies from their location along a ray is only possible if RA,DEC were incorrect, which is not true.

So the issue about the uncertainties in the 3rd dimension, i.e. the distances, then only amount to the question by how much such strings of galaxies along straight rays may be compressed along these rays.

Note we are talking about 3d polar coordinates, here

Fridger

[t00fri]

Then, maybe Selden's way is a better alternative to show the bubbles and walls, as a layer :

Selden_model.jpg

Yes for instance. Selden has the SDSS data, from which one then can see that there are further radial streaks partly merging nicely with the rays of galaxies from my database.

Fridger

[ElChristou]

Then, maybe Selden's way is a better alternative to show the bubbles and walls, as a layer :

Too bad those models are under some esoteric download system...

[Cham]

Then, maybe Selden's way is a better alternative to show the bubbles and walls, as a layer :

Too bad those models are under some esoteric download system...

Not at all, they are on the ML !

[ElChristou]

Not at all, they are on the ML !

Ah yes!

[Cham]

I decided to build my own champain bubbles, using the recent data from SLOAN (SD6) :

http://cas.sdss.org/astro/en/tools/search/SQS.asp

The model is matching very well Selden's version. I noticed a small stretch between both models, though. I suspect that Selden used the approximation [tex]d = z c /H_{0}[/tex], which is valid for [tex]z << 1[/tex] only. For my version, I used the comoving distance (for null spatial curvature : [tex]k = 0[/tex]) : [tex]D = 2 (c/H_{0}) (1 - 1/sqrt(1 + z))[/tex]. This gives D < d, for the redshift used. This is consistent with the small stretching I noticed on Selden's version (or maybe the radius he used in the DSC file is just sligthly too large for his models). Here's a preview, with the galactic plane layer activated :

hubble0.jpg

The model is nicely merging with Celestia's database :

hubble1.jpg

hubble2.jpg

[t00fri]

Martin,

its always good to understand BEFORE criticizing!

Immediately after reading your add-on plans, I had suggested you to use the Sloan DSS data:

I would approach such an analysis quite differently: Rather than merging tabulations from various rather old individual papers, I think one should read out instead the Sloan DSS data base in batch mode (which is offered).

I have also right away suggested that you should use the higher order comoving definition of distance, which you now correctly did...

You would have right away realized that the straight radial patterns in my Celestia database are NOT artefacts, but the onset of the famous large scale structure seen so clearly in the Sloan DSS.

The model is nicely merging with Celestia's database :

This way you had avoided to disqualify yourself with your previous incorrect criticism of my deepsky.dsc database... !

Fridger