Galaxies.dat update: 863 galaxies including Virgo Cluster

Paul · Post #1by **Paul** » 08.11.2002, 07:42

Get it here:
http://www.geocities.com/doctorshnub/galaxies.txt
Or here, for the version with the silly-looking blobs...

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

The installation instructions are in the top of the file, along with some other notes that I thought would be useful, not the least of which is a version number - so you can track which of my versions of galaxies.dat you are using.
The notes also mention that I have made my own alterations to the distance data stated in Tully's 'Nearby Galaxies Catalogue'. A few are Cepheid distance estimates, but some are offsets (along line of sight) to members of the larger clusters. Tully lists all cluster members as having the same distance, which lines them up in a plane (which is both unrealistic and looks terrible).
I have used a straightforward methodology to spread them out, the result of which is easily within limits of uncertainty - and of course it looks much better, especially when you are floating in the outskirts of M87 and look outwards. Now if only I could place some stars out there...

Post #2by **selden** » 08.11.2002, 12:21

Paul,

Thanks!

If one backs off far enough, it almost seems that one can see some of the voids and filaments that the really deep surveys have discovered.

Unfortunately, there really needs to be a way to turn up their luminosty more

Even with the cut-off magnitude turned up all the way, they're hard to see in a room with any light at all, and on my system at work, forgetaboutit (which is probably just as well

)

Guest · Post #3by **Guest** » 20.11.2002, 19:22

How can I change the luminosity of the galaxys? Like selden said, it's impossible to see them.

Post #4by **t00fri** » 20.11.2002, 19:52

Anonymous wrote:How can I change the luminosity of the galaxys? Like selden said, it's impossible to see them.

"Impossible" sounds like a very general statement;-). I can see these galaxies very well, for example. There are a couple of reasons on your side that might prevent you from seing them:

a) you simply forgot to switch galaxy rendering ON in the options dialog.

b) Brightness and/or contrast of your monitor are/is grossly misconfigured. There are lots of software tools available to adjust those two parameters correctly.

There is no button for changing the luminosity of galaxies. For more experienced users, a few commands in a PERL script may change it in galaxies.dat of course....

Bye Fridger

Guest · Post #5by **Guest** » 20.11.2002, 20:39

Hehe, galaxy rendering is ON :wink:

Adjusting brightness/contrast helps only a bit. It's still a spongy grey the galaxies are colored in. I'd like to have them in light white

Thx for the help anyways, would be nice to adjust that setting in Celestia itself the next version.

Post #6by **t00fri** » 20.11.2002, 20:55

Anonymous wrote:Hehe, galaxy rendering is ON :wink:

Adjusting brightness/contrast helps only a bit. It's still a spongy grey the galaxies are colored in. I'd like to have them in light white :?

Thx for the help anyways, would be nice to adjust that setting in Celestia itself the next version.

After many many years of practicing amateur astronomy with >=8 inch telescopes, I must say that I have never been able to view galaxies in "light white";-). Usually they look exactly: "spongy grey"...

Bye Fridger

Guest · Post #7by **Guest** » 20.11.2002, 21:59

You don't seem to get the point. It's about visibility here, not about reproducing the view from earth with it's limitations due to the equipment.

Post #8by **t00fri** » 20.11.2002, 22:35

Anonymous wrote:You don't seem to get the point. It's about visibility here, not about reproducing the view from earth with it's limitations due to the equipment.

No, I don't even less now. If you want to abstract from limitations due to equipment, then why do you want to see galaxies in "light white". They ARE NOT! They have all sorts of colors.

Bye Fridger

Post #9by **selden** » 20.11.2002, 22:45

Fridger,

Now you're picking nits

(to use what I've always thought to be a very strange expression o.O )

Of course we want to be able to see all the galaxies in all their colorful glory, with all of their billions and billions of stars and nebulae and gas clouds and....

sigh. someday. soon?

It just takes a bit more precision. And a little more computing power. And slightly better graphics displays. And just a few more hours of coding and, and and....

Post #10by **t00fri** » 20.11.2002, 23:04

selden wrote:Fridger,

Now you're picking nits ;) (to use what I've always thought to be a very strange expression o.O )

Nooooooooooooooooooo;-)

I was just naively answering to
Mr. Anonymous'

"You don't seem to get the point"...

Bye Fridger

Rassilon · Post #11by **Rassilon** » 20.11.2002, 23:04

No point in changing the galaxy models...Thier fine as they are...well maybe add a few more model variations

When stars are added then the brightness/color will appear but basically all the images we have to go by (save for hubble) are all as seen from the earth...Hubbles only difference there is no atmosphere...Now this I say should be added into Celestia...The atmospheres way of 'blurring' the objects as they are seen through a conventional telescope or the naked eye...Also during the day the dark side of objects or planets etc should blend in with the surrounding atmosphere and the colors muted to a mid tone level of sorts...

Paul · Post #12by **Paul** » 21.11.2002, 01:20

No point in changing the galaxy models...Thier fine as they are...well maybe add a few more model variations

Here's my wish list, in order:

1. Ellipticals which can actually be oriented :wink:

2. Brightness setting
3. Spiral arms slightly bluer and bulges/ellipticals yellower
4. Three spiral types - barred, grand-design, flocculent
5. Lenticular (S0) galaxies - these are quite common, and feature an armless disk with a bulge (and often a bar)
6. A new method of delineating arms with "dust cloud" sprites, whose shape isn't important (yet), only that they darken rather than glow.
7. Complete realism, eventually...

jgrillo2002 · Post #13by **jgrillo2002** » 21.11.2002, 01:41

I really dont understand the instructions on the txt. can you tell me what to do simply

Darkmiss · Post #14by **Darkmiss** » 21.11.2002, 01:46

Save the text as a text file.
then rename it too Galaxies.dat and replace the old one.

If you want proof, you can open the old Galaxies.dat with Notepad.

Guest · Post #15by **Guest** » 21.11.2002, 08:17

1. White is the invert color of black, therefore best to be distinguished from black (make it a light white = best visibility :!:

).

2. I am not opposed to colors as long as they are not dark, reason explained above.

This is the last post to explain to those who don't understand, no offence or name here :roll:

Darkmiss · Post #16by **Darkmiss** » 21.11.2002, 11:15

huh! what was that about :?:

alliance · Post #17by **alliance** » 25.11.2002, 19:35

im dl/ing it right now, does it work on celestia or some thing else?

btw im very impressed by your work!!! i love stars, and this gives me a chance to look around with ou leaving the comfort of my house...

add the new files and its a blast!!! but some bugs... some times the moon comes up really close to earth, around 12 meters, and i dont think that very realistice, and jupiter mars and earth are way way way too close to each other ( 15,000 k ), thanks alot for your time.

Post #18by **selden** » 25.11.2002, 20:12

Alliance,

Your comments are hard to understand since you left out the context.

alliance wrote:im dl/ing it right now, does it work on celestia or some thing else?

What are you downloading? Galaxies.dat? It is indeed an addon for Celestia, and works quite well. (If only galaxies could be made brighter...)

alliance wrote:btw im very impressed by your work!!! i love stars, and this gives me a chance to look around with ou leaving the comfort of my house...

Are you saying you're impressed by Celestia or one of the addons? I certainly agree that Chris has done a great job with Celestia. Most of the addons are very good, too.

alliance wrote:add the new files and its a blast!!! but some bugs... some times the moon comes up really close to earth, around 12 meters, and i dont think that very realistice, and jupiter mars and earth are way way way too close to each other ( 15,000 k )

Past the year 4000AD the highly precise orbital functions that Celestia uses are invalid, so Celestia reverts to using simple elliptical orbits. There's a bug in the way the Moon's orbit is calculated then because a typo makes it think the earth has the mass of the sun. Chris has fixed that in the next release, which is supposed to be available RealSoonNow.

Other than that, I don't know of any distance errors like you describe, unless you've loaded an Orrery addon that I recall someone defining. That would have replaced the default /data/solarsys.ssc and made all the distances small.

You have to be careful which add-ons you add and how you do it. Many of them make incompatible changes to Celestia's files. A redesign of Celestia's filesystem to accomodate all the different addons is being thought about.

In the meantime, it's too easy to damage the files that Celestia uses to describe its universe. I always copy Celestia's directory tree to another location and then make changes to the copy, never to the original downloaded version. That makes it easy to revert to something that is known to work. (Ignoring the minor bugs that we all like to complain about

)

If that's what's happened, you'll probably have to reinstall Celestia. Install it in a different directory and then copy over the files that you need to fix.

I hope this helps.

billybob884 · Post #19by **billybob884** » 25.11.2002, 21:11

now selden, i think your being a little too harsh :wink: