A script to mark ALL Fridger's galaxies

[Vincent]

This script is really interesting Cham.
With a few more celx commands, this kind of very informative scripts about DSO could be written with only 10 lines...

Indeed, the object:getinfo() celx command currently returns only 3 elements in the case of deepsky objects :
- type (= "deepsky")
- name
- radius

As a comparison, the same object:getinfo() command returns much more information in the case of stars :
- type (="star")
- catalogNumber
- stellarClass
- absoluteMagnitude
- luminosity
- radius
- temperature
- rotationPeriod
...

So it would be nice to have a few more information returned by the object:getinfo() celx command in the case of DSO, such as :
- catalogNumber
- subtype ("galaxy", "nebula", "opencluster",...)
- hubbletype ("S0", "Sa", "Sb", "Sc", "Sba", ...)
- absoluteMagnitude
...

Also, the celestia:getdeepsky(catalog, number) would return a specific deepsky object identified by its number, in the specified catalog "M", "NGC", "IC"... (as the celestia:getstar() command already does for stars)

I can try to work on it if Chris, Fridger, and the other devs think that it would represent a useful addition to celx. Just let me know...

[t00fri]

I can try to work on it if Chris, Fridger, and the other devs think that it would represent a useful addition to celx. Just let me know...

I am most enthusiastic about this!

++++++++++++++++++
Since long I am working to really fill the Celestia Universe with LOTS of those objects that belong there .
++++++++++++++++++

In my view it is really instructive and thus of high EDUCATIONAL value if --by the time-- Celestia offers a set of CELX scripts with the help of which one may investigate/display characteristic (statistical) properties of these objects populating the Universe.

What we really should address ASAP among the devs is to arrive at an adequate auto-adapting (!) set of STANDARD coordinate grids, including alt-azimuth, equatorial, /galactic/ coordinates. Such a grid system is overdue since YEARS!

As an example, Cham's nice display of my galaxies would have looked even more instructive, if the void wedge had become apparent as the equatorial region by means of a superimposed /galactic/ coordinate grid!

There is a host of related useful displays one can envisage with Lua:

1) e.g. also redshifts by means of colored dots ranging from white to (dark) red. Using Hubble's law, the redshift is available to good accuracy from the galaxy distance for many galaxies of my catalog. One might even want to input in addition a catalog with the /peculiar/ velocities which would allow to color-mark also the blueshifted galaxies (of our local group), where the peculiar velocities due to gravitational effects in galaxy clusters dominate over the redshifts due to the expansion of the Universe...

2) Cham's great overlay of the quasar locations in the MilkyWay.

3) asteroid belts are another great application, once we have incorporated thousands of asteroids. Here the problem is the (octree) culling, since asteroids are not stationary objects. But as I often wrote, I have many ideas here...Just need more time.

...

Bye Fridger

[buggs_moran]

But as I often wrote, I have many ideas here...Just need more time.

Don't we all...

[t00fri]

But as I often wrote, I have many ideas here...Just need more time.

Don't we all...

I am not so sure how many others would really know how to address THAT particular and pretty tough problem of octree culling of MOVING asteroids...Ever heard about action-angle variables, for example?

Bye Fridger

[ElChristou]

Tx Cham!

Indeed it's a pretty interesting rendering, but definitively something should be done at dev level because of the poor fps with the markers... Also as for the Galaxy labels a minimum of culling should be implemented to accentuate the 3D feeling...

I'm confident our Dev team will find something out for those problems

[Vincent]

OK,

I've added some of the new celx commands that I described in my previous post.
Here's a patch built against the current CVS : http://vincent.gian.club.fr/celestia/dso_info.patch

Cham's script can now be written in celx using the following lines :

Code: Select all

function mark_dso()
    ndso = celestia:getdsocount()
    i = 0
    while i < ndso do
        dso = celestia:getdso(i)
        hubbleType = dso:getinfo().hubbleType
      if string.find(hubbleType, "E") then
         dso:mark( "red", "circle", 1, 0.5 )
      elseif string.find(hubbleType, "Irr") then
         dso:mark( "yellow", "circle", 1, 0.5 )
      elseif string.find(hubbleType, "SB") then
         dso:mark( "green", "circle", 1, 0.5 )
      elseif string.find(hubbleType, "S") then
         dso:mark( "blue", "circle", 1, 0.5 )
      end
        i = i + 1
    end
end

celestia:unmarkall()
mark_dso()

I'm currently trying to make the markers' transparency vary according to the distance to the observer to accentuate the 3D feeling, as suggested by ElChristou...

[t00fri]

Neat!, Vincent.

Bye Fridger

[Cham]

We also need the markers to be drawn on the background, BEHIND foreground objetcs.

If you navigate inside our solar system, the markers are getting very confusing, if you have, say, the Earth on the foreground.

[ElChristou]

Tx, Vince, works great!

I split your celx by type, don't know if the code is right but it works fine...


E galaxies:

Code: Select all

celestia:print(" M a r k i n g   E l l i p t i c a l   G a l a x i e s  . . . ", 5, 0, 0, 0, 0)


function mark_dso()
    obs = celestia:getobserver()
    ndso = celestia:getdsocount()
    i = 0
    while i < ndso do
        dso = celestia:getdso(i)
        hubbleType = dso:getinfo().hubbleType
      if string.find(hubbleType, "E") then
         dso:mark( "red", "disk", 1, 0.5 )
      end
        i = i + 1
    end
end

mark_dso()


S galaxies:

Code: Select all

celestia:print(" M a r k i n g   S p i r a l   g a l a x i e s  . . . ", 5, 0, 0, 0, 0)


function mark_dso()
    obs = celestia:getobserver()
    ndso = celestia:getdsocount()
    i = 0
    while i < ndso do
        dso = celestia:getdso(i)
        hubbleType = dso:getinfo().hubbleType
      if string.find(hubbleType, "S") then
         dso:mark( "blue", "disk", 1, 0.5 )
      end
        i = i + 1
    end
end

mark_dso()


SB galaxies:

Code: Select all

celestia:print(" M a r k i n g   B a r r e d   S p i r a l   G a l a x i e s  . . . ", 5, 0, 0, 0, 0)


function mark_dso()
    obs = celestia:getobserver()
    ndso = celestia:getdsocount()
    i = 0
    while i < ndso do
        dso = celestia:getdso(i)
        hubbleType = dso:getinfo().hubbleType
      if string.find(hubbleType, "SB") then
         dso:mark( "green", "disk", 1, 0.5 )
      end
        i = i + 1
    end
end

mark_dso()


Irr galaxies:

Code: Select all

celestia:print(" M a r k i n g   I r r e g u l a r  g a l a x i e s  . . . ", 5, 0, 0, 0, 0)


function mark_dso()
    obs = celestia:getobserver()
    ndso = celestia:getdsocount()
    i = 0
    while i < ndso do
        dso = celestia:getdso(i)
        hubbleType = dso:getinfo().hubbleType
      if string.find(hubbleType, "Irr") then
         dso:mark( "yellow", "disk", 1, 0.5 )
      end
        i = i + 1
    end
end

mark_dso()


if needed an unmark all (I remove the function in each previous)

Code: Select all

celestia:print(" U n m a r k i n g   a l l  . . . ", 2, 0, 0, 0, 0)
celestia:unmarkall()


[ElChristou]

Remember Vincent's Edu tools? Why not a specialized tool for DSO survey?

It could look like this: (it's just a quick start, I'm sure Fridger will have better ideas of the functions of such a tool)

[ElChristou]

No? too bad...

[ElChristou]

BTW, can Vincent's patch be integrated to CVS?

[starfleetengineer]

My 1.4.1 celestia crashes when I run these celx scripts. I assume this is because they are using 1.5.x features.
Can someone tell me what is the 1.5.x specific feature(s) being used?

Perhaps I can rewrite for 1.4.1 by excluding the 1.5.x feature(s)...

[t00fri]

My 1.4.1 celestia crashes when I run these celx scripts. I assume this is because they are using 1.5.x features.
Can someone tell me what is the 1.5.x specific feature(s) being used?

Perhaps I can rewrite for 1.4.1 by excluding the 1.5.x feature(s)...

For this celx script to work, you first need to implement Vincent's patch (which he posted a few mails back) into the current CVS version. One reason for the patch is to properly read out required info about the DSOs. So I don't see how you can get along without the patch.

Bye Fridger

[Vincent]

I'll commit the changes into CVS when I'm back home, in a few hours...
Users who can't compile the CVS version can still use Cham's cel version of the script, or wait for the release of 1.5pre3.

[Cham]

Thanks Vincent. I recompiled Celestia, and the new script commands are working very well. I would prefer an orange color for the elliptical galaxies, like in my cel script, but this is just a matter of taste.

Now, these galactic markers are VERY usefull. With their help, I located a nice galactic cluster which I would never have found without the markers ! By moving arbitrarily in the markers, I suddenly noticed some high concentration of red dots :



Traveling closer carried out to this cluster :



Pretty nice !

Unfortunately, this cluster isn't a real one, since looking at it from the side shows a perfectly aligned set of galaxies, which is, of course, associated to some poorly estimated distances :



Well, such is astronomy.

By the way, I think that this script (Vincent's version, since it's much smaller than mine) should be included in the official distribution, and we URGENTLY NEED a script menu in Celestia, associated to a "scripts" folder. This galactic script is a good example why.

[starfleetengineer]

For this celx script to work, you first need to implement Vincent's patch (which he posted a few mails back) into the current CVS version. One reason for the patch is to properly read out required info about the DSOs. So I don't see how you can get along without the patch.

Bye Fridger

Thanks for the explanation. I agree with you...these scripts will therefore never work in 1.4 version.

I like the idea of being able to selectively enable different types of objects as ElCristou contributed. Some key bindings would be nice in this context, however I think we are already running out of available keys in Celestia (as I found with my Warpdrive).
I think we should give some time for scripts such as these to mature with ideas from other people before including in a distribution, if at all. IMO they need to be fairly generic before you can justify including in a distribution. (ie. there are many other classes or situations of objects in Celestia for which it may be useful to mark and categorise)
Useful though they are, I also don't see any great advantage or need to include scripts such as these in a distribution unless they were bound to keys, and there aren't many free keys available.

Personally, I'm quite happy to just have them as extras.
Thanks for the contributions guys. I'll look forward to using these in 1.5, whether as extras or part of the release.

SFE

[starfleetengineer]

BTW,

I think the journey I suggested earlier in this post: http://celestiaproject.net/forum/viewtopic.php?p=84433#84433

may be quite interesting with these coloured markers enabled.

(The URL is a 1.4.1 version, but this shouldn't matter at the scales involved )

[t00fri]

As I wrote already elsewhere, another similarly interesting application
would be scripts that mark the 10000+ asteroids from the official catalog (once they are all implemented ).

I had done such a plot of the asteroid belt already years ago



based on the official catalog
ftp://ftp.lowell.edu/pub/elgb/astorb.dat.gz

I have read out by means of PERL (of course )

Another nice apllication would be to color the galaxies according to their redshift z that one may easily obtain. One may color them increasingly read for increasing redshift, for example...

Bye Fridger

[ElChristou]

...Another nice apllication would be to color the galaxies according to their redshift z that one may easily obtain. One may color them increasingly read for increasing redshift, for example...

Could you release a new deepsky.dsc with those new datas? I'm pretty sure Vincent could modify CVS just like he does recently to extract and use those new arguments via celx...