Celestia Forums

Here's an updated galaxies.dat with most of the larger/nearer galaxies in galaxy groups within about 50 Mly. It also contains a major portion of the Milky Way's globular clusters, rendered as tiny galaxies which works quite nicely.

http://www.geocities.com/doctorshnub/galaxies.txt

You'll have to change the file suffix to .dat to get it to work, of course.
Don't forget to turn on galaxy labels ('e'). It's indeed a pity you can't crank up galaxy brightness...

Enjoy,
Paul

Hi Paul,

Nice work! :D I'm surprised that I am the first one to reply... It's great to see the Celestia universe expanding towards the whole observable universe ;)

Hi Buzz,

Glad you like them! As it happens, I posted a slightly less populated version of my galaxies.dat a few months ago and got almost no response then. I just don't think that people are that interested, I suspect it has something to do with the representation of galaxies being so limited in Celestia. I'd really like it if Chris gave Celestia's galaxies:

1. More morphological parameters, i.e. bar/bulge size, number and shape of spiral arms.
2. Some coloured 'wispy' sprite particles to delineate dark nebulae and HII regions along spiral arms, and more colour variation overall, e.g. yellower sprites for the bulges/bars, and also for elliptical galaxies.
3. An overall brightness setting like that for stars.

I agree! I do believe these wishes have been expressed before and that Chris is aware of them. Maybe the comet tails that are promised will produce some spin-off...

Paul wrote:Hi Buzz,

Glad you like them! As it happens, I posted a slightly less populated version of my galaxies.dat a few months ago and got almost no response then. I just don't think that people are that interested, I suspect it has something to do with the representation of galaxies being so limited in Celestia. I'd really like it if Chris gave Celestia's galaxies:

1. More morphological parameters, i.e. bar/bulge size, number and shape of spiral arms.
2. Some coloured 'wispy' sprite particles to delineate dark nebulae and HII regions along spiral arms, and more colour variation overall, e.g. yellower sprites for the bulges/bars, and also for elliptical galaxies.
3. An overall brightness setting like that for stars.

Item 3 is very easy to do and I'll add that for 1.2.5. Additional parameters to control the shape of galaxies is somewhat more difficult, since the shapes are all precomputed. I'll see what I can do, as this is important for getting a more realistic Milky Way. Adding color variations and dust regions will require sorting of the sprite particles, and that's computationally expensive. However, it might be possible to only resort the particles when the viewer position changes dramatically. For the Milky Way, if you're just zooming around the stars in the HIPPARCOS catalog, it should never be necessary to resort.

--Chris

Item 3 is very easy to do and I'll add that for 1.2.5.

Excellent! Thanks Chris, this will be great!

Additional parameters to control the shape of galaxies is somewhat more difficult, since the shapes are all precomputed. I'll see what I can do, as this is important for getting a more realistic Milky Way.

So I guess I'm lucky we live inside a galaxy then...

Well after adding a few a day for the last couple of weeks, the total has grown to 155 galaxies and 51 globulars. Almost all major galaxy groups and clusters within 100Mly are now included, although there are a great deal left to go.
I've been using Tully's 'Nearby Galaxies Catalogue' which lists over 2300 galaxies (just search in VizieR for 'nearby galaxies catalogue' ).

http://www.geocities.com/doctorshnub/galaxies.txt

Don't forget to rename the '.txt' to '.dat', and back up your old galaxies.dat file too.

It sounds as if you spent a lot of time generating this list! You should have credit for donating your time, but why not write a program to generate the list automatically, from e.g. the LEDA data base (or Tully's for that matter)?

/Alexis

Nice work Paul

Dosn't look so lonely out there now, when you zoom out far enough

thank you

It sounds as if you spent a lot of time generating this list! You should have credit for donating your time, but why not write a program to generate the list automatically, from e.g. the LEDA data base (or Tully's for that matter)?

Well, added up I guess it amounts to a fair bit of time, but currently there are quite a few advantages to entering it manually:

1. I can tweak things to be more accurate. Some surveys have better distances for some galaxy groups, but are incomplete. There are even errors here and there. Some of Tully's distance estimates would mean improbable galaxy sizes.
2. I can tweak things to look better. For instance, I have represented M104, the Sombrero Galaxy, with two "galaxies" to make it look more like the real thing.
3. I can omit objects that Celestia can't currently render correctly. Some nearby dwarf galaxies are quite diffuse (i.e. large and faint), but Celestia renders them far too brightly. (Or is there a galaxy property for this?)
4. Examining all these galaxies individually is fascinating! A lot of the galaxies I've entered have been interesting in some way, and some I'd never known about before, like NGC 7727. I really hope they put 7727 under Hubble's watchful eye in the future.

So, I wonder when Chris is going to write a shader for random galaxy clusters, so I can start entering the Abell catalogue...

Really great work, i cannot say it enough, too bad they all look the same.

I was also wondering, what could normally be found between galaxies? Cuz now space seems a very empty. You appear to fly through black only. Thats a bit of a shame.

I also remember seeing an animation of a flight flying through all clusters of galaxies, there were so many of them that it gave the same effect as flying through the densely(mapped) populated lightyears around the sun. It would be great if celestia could operate on a scale like that. Being able to zoom out from the sun to the solar system to the galaxy to clusters of galaxies.

That the universe seems empty between the galaxies in Celestia is quite accurate, because the intergalactic universe is very empty, at least of normal (baryonic) matter. Interstellar space has a matter density of about one atom per cubic centimetre, while intergalactic space has an atomic density of about one atom per cubic metre, i.e. a million times less! And intercluster space is even less dense. Sorry, but outer space is really empty!

If you want to fly through the galaxies as you fly through a starfield, just increase your velocity a million times or so (or equivalently, speed up time a million times). There's no need to change your field of view or anything (i.e. to "zoom out"). Of course, you need lots of galaxies - in 3D - for this to be a great effect.

/Alexis

nice work Paul,
As celesitas universe gets bigger it really helps you to feel small.

whats more is it will be really cool once we start getting stars in the other galexies!


Mike M.

As celestias universe gets bigger it really helps you to feel small.

Really? I find that as Celestia's universe gets bigger, what I feel is not the insignificance of the body, but the enormous scope of imagination. It's quite amazing that a bunch of lifeforms sitting on a little blue planet somewhere can visualise the entire Universe inside their heads.

damn right there, I really should have said, wow look how big it is.

Dwingeloo 1
?
Who named that galaxy?

Dwingeloo is a village in the Netherlands where a foundation for astronomical research is based. It's also the name of a radio telescope.

wow thanks you learn something every day

http://icarus.stsci.edu/~ferguson/resea ... /dogs.html

I really can't wait until the entire currently known galaxies are mapped in celestia. Damn. I'd love it!

I Love the galaxies so much because i think they have more character than stars. They have a different form and thickness. Stars are simply spheres.

Now it's time for a galaxy browser as well.