My much improved galaxy database for download &TESTING

[Cham]

I don't think there's an easy solution to the selection problem. Markers can't be clicked. The only "natural" way is to turn around, select a clickable object and then repeat the process until we get close enough of the object we want to see. Actually, I think this is even part of the fun, with Celestia. It feels like real exploration !

[Vincent]

Well, another easy workaround would be to increase the limiting magnitude to its maximum value with ']'. This really makes galaxies more easily selectable. It also increases the number of labelled galaxies in the neighborood of the observer. Then, one can use 'E' to activate/unactivate the galaxy labels...

I'll investigate the problem more deeply, as well as your new galaxy catalog, when I'm back from my 3 days off in Paris...

[t00fri]

Well, another easy workaround would be to increase the limiting magnitude to its maximum value with ']'. This really makes galaxies more easily selectable. It also increases the number of labelled galaxies in the neighborood of the observer. Then, one can use 'E' to activate/unactivate the galaxy labels...

I'll investigate the problem more deeply, as well as your new galaxy catalog, when I'm back from my 3 days off in Paris...

But that exactly doesn't work at such large distances as one would start from with z-dist.celx. The lever arm is simply too small. That's the first one tries of course.


I prefer the following 3rd workaround. After starting with z-dist.celx, hitting ESC and then returning to sol (H G), one still sees all the galaxies marked, but now one can enjoy the usual label display thresholds. Moreover, activating the constellation boundaries is also a big help for orientation. My above image displaying the various galaxy clusters is such an example.


Bye Fridger

[Cham]

Fridger,

I've found a bug in your new database :



Both galaxies DDO 226 and IC 1574 appears to be the same object, with a slightly different coordinate.

Also, Vincent's script shown below doesn't work correctly anymore, I don't know why :

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

mark_dso()

[t00fri]

Fridger,

I've found a bug in your new database :


...

Thanks, that is the typical kind of things we have to look out for, since they are beyond my influence:

++++++++++++++++++
The general rule with galaxy nomenclature in ALL catalogs, including the new 'catalog of neighboring galaxies', is to place the NGC and IC names as the principal names if a NGC/IC name assignment exists.
++++++++++++++++++

In the ZCAT catalog this was correctly done (IC 1574, DDO 226).

However in the new ,neighboring galaxies' catalog DDO 226 was INCORRECTLY placed as the first and only name.

That error created the double object

This should be an exception, however and the fix is trivial.

It is comforting to see how close the two objects lie despite their distance being taken from two different sources, and in one case calculated as the comoving (cosmological) distance from the given redshift.

The difference in distance is only a /fraction/ of their size...

Bye Fridger

[t00fri]

How do people feel about the nomenclature for the many dwarf galaxies in the Local Group. Various different ones are popular:

Right now I used only the constellation name in full:

Sculptor, Fornax, Draco, Carina,...

should I add the word Dwarf or not? Another option is
to just use 'Dw' or 'dw' acronyms after the names.

In addition there are often 2 variants, e.g. an 'Irr' variant and a dSph (spheroidal morphology). So naming becomes quite tricky and varies greatly among catalogs.

e.g

Sag dSph

is the most popular...
In general I tended to use a name that may be found also e.g. in the NED and Simbad interactive databases.
But it does not work in all cases since also NED and Simbad name recognition is sometimes mutually exclusive...

Bye Fridger

[Vincent]

Also, Vincent's script shown below doesn't work correctly anymore, I don't know why :

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

mark_dso()

Cham,

This script has been updated several times, following the changes in CVS.
I've just checked in a last change into CVS that makes celx distinguish between galaxies, nebulae or openclusters.

You can update your source from CVS, then use the following script to mark all galaxies according to their Hubble type :

Code: Select all

function mark_galaxy_types()
   for dso in celestia:dso() do
      if dso:getinfo().type == "galaxy" then
         hubbleType = dso:getinfo().hubbleType
         if string.find(hubbleType, "E") then
            dso:mark( "red", "disk", 1, 0.7 )
         elseif string.find(hubbleType, "Irr") then
            dso:mark( "yellow", "disk", 1, 0.7 )
         elseif string.find(hubbleType, "SB") then
            dso:mark( "green", "disk", 1, 0.7 )
         elseif string.find(hubbleType, "S") then
            dso:mark( "blue", "disk", 1, 0.7 )
         end
      end
    end
end

celestia:unmarkall()
celestia:setrenderflags { markers = true }
mark_galaxy_types()

I'll post some updated versions of the different scripts we wrote about DSOs (and even more... ) on the appropriate thread : http://celestiaproject.net/forum/viewtopic.php?p=85531

[Cham]

Thanks Vincent,

it's working now.