CVS deepsky.dsc

[Brendan]

I looked at the deepsky.dsc file and it had M 110 be 10 times further away, at 20 million light years, than M 31. In the 1.3.2 version, M 31, M 32 and M 110 are all at the same distance away, at over 2 million light years, because M 32 and M 110 orbit M 31. Do the catalogs really show M 110 that far away?
The small Magellanic cloud also appears twice because there are two entites in the data file for it. One is Small Magellanic Cloud / NGC 292 at the end of the file. The other is NGC 292 near the beginning of the file. The second one appears further away in the same part of the sky as the first one. Were the entites from the old deepsky.dsc file put onto the end of the new one?

[symaski62]

CVS deepsky.dsc ( V1.3)

Code: Select all

 # Andromeda / NGC 224   
 Galaxy "M31"   
 {   
         Type "Sb"   
         RA        0.712   
         Dec      41.27   
         Distance  2.9e6   
         Radius   75000   
         Axis [ -0.596 -0.191 0.780 ]   
         Angle 195   
 }   
   
 # Triangulum spiral / NGC 598   
 Galaxy "M33"   
 {   
         Type "Sb"   
         RA    1.565   
         Dec  30.65   
         Distance 3e6   
         Radius 30000   
 }   
   
 # NGC 205, satellite of M31   
 Galaxy "M110"   
 {   
         Type "E5"   
         RA    0.6883   
         Dec   41.683   
         Distance 2.9e6   
         Radius 8500   
         Detail 0.5   
 }   
   
 # NGC 221, satellite of M31   
 Galaxy "M32"   
 {   
         Type "E2"   
         RA    0.712   
         Dec  40.867   
         Distance 2.9e6   
         Radius 4000   
         Detail 0.5   
 }   
   
 # M81 / NGC 3031   
 # Distance estimate based on Hipparcos results and HST   
 # observations of Cepheid variables.   
 Galaxy "M81"   
 {   
         Type "Sb"   
         RA 9.9267   
         Dec 69.067   
         Distance 1.2e7   
         Radius 35000   
 }

[t00fri]

I looked at the deepsky.dsc file and it had M 110 be 10 times further away, at 20 million light years, than M 31. In the 1.3.2 version, M 31, M 32 and M 110 are all at the same distance away, at over 2 million light years, because M 32 and M 110 orbit M 31. Do the catalogs really show M 110 that far away?
The small Magellanic cloud also appears twice because there are two entites in the data file for it. One is Small Magellanic Cloud / NGC 292 at the end of the file. The other is NGC 292 near the beginning of the file. The second one appears further away in the same part of the sky as the first one. Were the entites from the old deepsky.dsc file put onto the end of the new one?

Brendan,

a lot of precision work went into the distance determination of my galaxy data set. On the whole this can hardly be compared in accuracy with what existed in 1.3.2 for the few galaxies in deepsky.dsc.

Still there are remaining problems that will be continuously improved as soon as suitable catalogs become available or known to me!

M 110 is one such example, while M31 and M32 in my catalog already involve the /very best/ distances available in the professional literature! I used as many as four different methods for the distance with cross checks between them if possible.

There is still one "bad" method used as a naive replacement for the cases that good/reliable distances were lacking in the big-size catalogs. M110 uses that method unfortunately.

Please remember: I shall NOT touch any of my data by hand since I want to retain total transparency wrto the best published catalogs. But this method for sure will end up with a very up-to-date catalog of galaxies. It just takes some more time.

The specific challenge in my galaxy project comes from the requirement to get 10000+ galaxy distances right and not just 5 or 6 as in the deepsky.dsc file of 1.3.2.

This request poses entirely new constraints just as our parallel rendering project that also focusses on very many objects AT ONCE.

As to the multiple entry issue (SMC...), this is also still in a primitive stage, since most galaxies exist with different names and require extensive cross-referencing. This again is still missing in the code. But sure enough it will come.

As a primitive workaround I just threw in the SMC, LMC and Milky Way entries from the 1.3.2 catalog at the end of my file. These data are not very accurate however and thus there are visible differences between NGC 292 and SMC.


Bye Fridger

[Brendan]

Are there any catalogs with the nearby small galaxies including satellites of the Milky Way and the Andromeda? Could they be added to deepsky.dsc? If there are no big catalogs with those galaxies, I'll make an addon for them.

[selden]

There aren't any DSC catalogs, except for what's included with Celestia.

A quick search didn't turn up any astronomical catalogs that include the most recently discovered Milky Way satellites like the Canis Major and Saggitarius that are in the process of being accreted, although there are individual articles about them.

Here are a couple to get you started:

Nearby Galaxies, by Schmidt and Boller (1992), indicates which are in the Local Group:
http://articles.adsabs.harvard.edu/cgi- ... etype=.pdf

Nearby Galaxies Catalogue, by Tully (1988):
http://nvo.gsfc.nasa.gov/archive/catalogs/7/7145/

[t00fri]

Are there any catalogs with the nearby small galaxies including satellites of the Milky Way and the Andromeda? Could they be added to deepsky.dsc? If there are no big catalogs with those galaxies, I'll make an addon for them.

My extended version of deepsky.dsc (25000+) galaxies includes many small galaxies belonging to the local group, notably also to LMC and SMC.

The highly cut-down version for the official distribution will only have a few left, I guess, due to the applied magnitude cut.

Bye Fridger