GAIA to SpaceEngine catalogs

PlutonianEmpire · 16 Nov 2018 03:55

I was hoping the 2m would be fixed too because I still have this problem when I have 2M installed: Stars that shouldn't exist or shouldn't be that bright show up in weird spots in our sky with weird names:
You might have an outdated version.

Nope. Redownloaded to be sure, no change at all from what I did have

16 Nov 2018 04:33

Updated some clusters in paks 800k, 3M, 4M and 5M.

You could try the filtering in Gaia Archive with:

WHERE r_est < 100000 AND radius_val > 0 AND phot_g_mean_mag > 8.5 and parallax > 0

'phot_g_mag > 8.5' ensures that most Hipparchos stars are excluded and 'parallax > 0' should filter out most stars with incorrect distances!

YouTube · 16 Nov 2018 07:05

'phot_g_mag > 8.5' ensures that most Hipparchos stars are excluded and 'parallax > 0' should filter out most stars with incorrect distances!

Filtering by parallax means nothing lol. All stars have a parallax > 0. Parallax is the angle formed by the apparent shift of the background in relation to the object viewed from two different positions. The distance can then be calculated via trigonometry. No parallax would mean a star located at infinity distance!

Also I want to still get the hipparcos stars in gaia to correct the distances for the hipparcos catalog as gaia is more accurate.

I was hoping the 2m would be fixed too because I still have this problem when I have 2M installed: Stars that shouldn't exist or shouldn't be that bright show up in weird spots in our sky with weird names:
You might have an outdated version.
Nope. Redownloaded to be sure, no change at all from what I did have

Weird. I'll take a look into it.

YouTube · 16 Nov 2018 09:43

I was hoping the 2m would be fixed too because I still have this problem when I have 2M installed: Stars that shouldn't exist or shouldn't be that bright show up in weird spots in our sky with weird names:
You might have an outdated version.
Nope. Redownloaded to be sure, no change at all from what I did have

Ok, so yeah, 2M still had wrong RA. Fixed now. Also fixed 800k being wrong file

.

16 Nov 2018 11:27

All stars have a parallax > 0.

NO!
Quote from the Gaia FAQ:

Why are some parallaxes less than zero?

Negative parallaxes are caused by errors in the observations. Even if a negative distance has no physical meaning, there are a certain number of stars expected to have negative parallaxes just from an error propagation perspective. The negative parallax tail is a very useful diagnostic on the quality of the astrometric solution. Further details can be found here and here.

YouTube · 16 Nov 2018 11:38

All stars have a parallax > 0.
NO!
Quote from the Gaia FAQ:
Why are some parallaxes less than zero?

Negative parallaxes are caused by errors in the observations. Even if a negative distance has no physical meaning, there are a certain number of stars expected to have negative parallaxes just from an error propagation perspective. The negative parallax tail is a very useful diagnostic on the quality of the astrometric solution. Further details can be found here and here.

Yes my mistake. What I meant was getting the parallax to determine the error in the parallax is not very useful. Instead, there is a parallax_error value that can be fetched from Gaia directly to calculate relative error %.

Edit: Also I should add that not all stars in a messed up cluster have a parallax less than 0. In fact, most have positive parallaxes, with an error that sometimes is even relatively small.

Edit 2:Also in real life, negative parallaxes are not real! Negative in measurements caused by the uncertainty means that the angle could be in the opposite direction.

16 Nov 2018 11:50

You should also check if parallax > 0, because some stars with parallax < 0 may still have reasonable parallax error.

A-L-E-X · 16 Nov 2018 16:55

Thanks Vladimir. I am wondering if I should download the GAIA add on because it was listed that the spectral types of the stars is not known so the colors might not be accurate. Maybe they can be crossmatched to other catalogs that do include the spectral data and other stellar properties.

Maybe eventually we could have a monthly updated plugin that would update the exoplanets that have been currently discovered rather than having to add individual exoplanets.

17 Nov 2018 09:19

What I meant was getting the parallax to determine the error in the parallax is not very useful.

Maybe you should nevertheless follow SpaceEnigneer's advice!

You should also check if parallax > 0, because some stars with parallax < 0 may still have reasonable parallax error.

YouTube · 24 Nov 2018 09:26

I made a showcase video.
[youtube]-dsFHuTaALY[/youtube]

Should add a little warning that there is quite a bit of flickering. Video was super compressed as original file size was unbelievably massive. It was still really big after being compressed. (15GB raw, compressed.) Watching the video in 1440p reduces that effect to certain degree.

Ensabahnur · 24 Nov 2018 10:55

Amazing video man, truly breathtaking!

N0B0DY · 29 Nov 2018 10:45

Cont'd from here (cause it was getting off topic there):

Guys its (probably) not (just) the cpu.. the program runs out of usable RAM. The moment it hits 3+ gigs of RAM usage it quits to desktop. I have a monster CPU and have the same fate.. I tried the 5M database and even when I disable proc+cat. galaxies, proc.stars & proc clusters I can go up to ~10.5 Magnitude (veery slowly) and then desktop.. If the above are enabled I can not even dream of 10 magnitude: ~8-9 and desktop.. (all this @ 5760x1080 resolution as I have 3 TVs..).
Is the GAIA add on worth it in your opinion even if the spectral classes and types of stars is randomized? And is it recommended to turn off all procedural stuff?
I dont mind limiting stars to around Mag 8.5, thats the dimmest the human eye can see anyway under no light pollution.
I dont use a very high resolution on the monitor I run it on, it's 1280x1024. I have all very high settings enabled and a 6 GB video card and 16 GB RAM.

The Gaia catalog is definitely worth it IMHO. It is just not optimized yet, neither is SE for this job. As Space Engineer mentioned in a previous post not even 0990 will be ready for this task. Even Gaia is not completed as all data are not yet processed. In its final form there will be approximately 1 billion stars. SE will need to be adapted to be able to accept such huge catalog(s). Space Engineer is a coding master & magician so I am confident SE will eventually include the Gaia catalog in all of its glory.

A-L-E-X · 30 Nov 2018 00:19

Omg thats huge, one billion stars is more massive than any planetarium program I know of.

One question I have is when the data is fully processed will all the spectral types and classes of stars be known? I would hope that was part of the initial collection of data, as thats pretty essential. It's pretty easy to determine stellar class and color using photographic data (B-V) and absolute magnitude and distance.

YouTube · 30 Nov 2018 08:29

Omg thats huge, one billion stars is more massive than any planetarium program I know of.

One question I have is when the data is fully processed will all the spectral types and classes of stars be known? I would hope that was part of the initial collection of data, as thats pretty essential. It's pretty easy to determine stellar class and color using photographic data (B-V) and absolute magnitude and distance.

We're going to have to wait until the next gaia release for proper stellar types and classes.

30 Nov 2018 10:23

It's pretty easy to determine stellar class and color using photographic data (B-V) and absolute magnitude and distance.

No, it is not. How would you determine to whuch branch star belogs, if those "branches" are so fuzzy? Only white dwarfs can easily be classified (well, most of them). Red giants have many "luninosity class" branches, which are not visible here. Some stars even changes their class!
[youtube]Pcy4U5uvL8I[/youtube]

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