Celestia Forums

Happy Newyear to all of you!!

When going around the deepsky with Celestia I've found some weird types of galaxies, like cE0pec and E0+*3.
I've take a closer look into deepsky.dsc file and found 28 different kind of galaxie types:
3S, 4S, 5C, cE0pec, E0, E0+*3, E1, E2, E3, E4, E5, E6, Irr, S0, S0?, S0+S0, Sa, Sb, SB, SB+C?, SBa, SBb, SBc, SBR, Sc, Sc?, Scm and Spec.
Deepsky.dsc is version 1.7 belonging to FT1.2 version of Celestia.

In galaxy.cpp the following code can be found:
static GalaxyTypeName GalaxyTypeNames[] =
{
{ "S0", Galaxy::S0 },
{ "Sa", Galaxy::Sa },
{ "Sb", Galaxy::Sb },
{ "Sc", Galaxy::Sc },
{ "SBa", Galaxy::SBa },
{ "SBb", Galaxy::SBb },
{ "SBc", Galaxy::SBc },
{ "E0", Galaxy::E0 },
{ "E1", Galaxy::E1 },
{ "E2", Galaxy::E2 },
{ "E3", Galaxy::E3 },
{ "E4", Galaxy::E4 },
{ "E5", Galaxy::E5 },
{ "E6", Galaxy::E6 },
{ "E7", Galaxy::E7 },
{ "Irr", Galaxy::Irr },
};

Are those 28 galaxy types right??

I've found the following information about these morphological types:
E=Elliptical; S0=Lenticular; Sa,Sb,Sc,Sd=Spiral;
SBa,SBb,SBc,SBd=Barred Spiral; Irr=Irregular; dE=Dwarf Elliptical;
dSph=Dwarf Spheroidal.
What is the difference between an a, b or c type galaxie and what is the meaning of the number after "E"?(like E4)?

HB,

many thanks for going through deepsky.dsc. so carefully. With 10600 objects it's hard to examine every single one

Indeed, in the various extended Hubble schemes that are in use, the nomenclature is quite horrendously involved. What you spotted are some isolated "punch throughs" relative to my rather complex PERL filter that was to convert /all/ of these extended designations into simple Hubble scheme names.

As soon as I have "resurrected" entirely from my nasty flu that got me out of traffic during most of last week, I'll fix these leftovers...

Only the names you quoted from the code (galaxy.cpp) are supposed to appear in deepsky.dsc.

Presumably, I made some slight last minute modification of the PERL filter which cause these additional 12 types to slip through.

Happy New Year,
Bye Fridger

Fridger,

I hope you get well very soon!!

Do you want to have the corresponding galaxie catalognumbers in order to find the faulty types back more easily??

HB wrote:Fridger,

I hope you get well very soon!!

Do you want to have the corresponding galaxie catalognumbers in order to find the faulty types back more easily??

Many thanks! While PERL can easily track those, too, it may still be useful as a cross check.

Bye Fridger

Fridger,
For your convinience, here it is.

HB wrote:Fridger,
For your convinience, here it is.

Code: Select all

FirstName  Name                                            Type
NGC 1741A  NGC 1741A:MCG 1-13-45:MK 1089:ARP 259           Scm
NGC 2605   NGC 2605                                        S0?
NGC 3165   NGC 3165:UGC 5512:MCG 1-26-23:ZWG 36.63         Scm
NGC 6271   NGC 6271:MCG 5-40-16:ZWG 169.21                 S0?
NGC 5860   NGC 5860:UGC 9717:MCG 7-31-33:MK 480            S0+S0
IC 186-1   IC 186-1:IC 186A:MCG 0-6-20:ZWG 387.23          S0?
IC 186-2   IC 186-2:IC 186B:MCG 0-6-21:ZWG 387.23          S0?
IC 625     IC 625:MCG 4-26-1:ESO 501-80                    Sc?
IC 656     IC 656                                          E0+*3
IC 1003    IC 1003:UGC 9190:ZWG 47.24:MK 1381              cE0pec
IC 1370    IC 1370:ZWG 375.21:ZW 111                       5C
IC 2431    IC 2431:UGC 4756:MCG 3-23-30:MK 1224            4S
IC 2786    IC 2786:MCG 2-29-24:ZWG 67.69                   S0?
IC 3284    IC 3284:ZWG 70.55:VCC 736                       SBR
IC 3960A   IC 3960A:MCG 5-31-56                            S0?
IC 4363    IC 4363                                         SBR
IC 4838    IC 4838:ESO 141-45:AM 1912-614:IRAS 19122-6142  Spec
IC 4918    IC 4918:ESO 233-16                              S0?
IC 5021    IC 5021:ESO 186-61:AM 2029-544                  Spec
IC 5022    IC 5022:ESO 47-5                                SBR
IC 5178    IC 5178:ESO 532-31:MCG 4-52-22                  SB+C?
IC 5223    IC 5223:UGC 12055:ZW

G 404.19:NPM 1              3S

Many thanks, HB,

that IS going to be useful! Interesting that most of the penetrators were from the IC catalog!
I'll work on that today and tomorrow and let you know when I have committed a revised version to CVS.

Bye Fridger

Fridger,

Unfortunatly, the list of wrong galaxy type names where not complete,
The galaxies of type SB are missing.

So, here they are:

Hi HB,

indeed I confirm that these are all the "bad guys".
I just inserted into my PERL script (deepsky.pl, CVS) the four lines



whence only your 50 "bad guys" are printed out from the total of 10600 galaxies...Now I simply have to tune the PERL filter such that the output becomes NIL

Cheers,
Fridger

Hi HB,

this is to report that I have just committed a revised deepsky.dsc (and its associated PERL script, deepsky.pl) to CVS for the forthcoming maintenance release celestia-1.4.1. After many cross-checks I am now certain that all extended Hubble type acronyms are correctly converted into simple Hubble scheme syntax.

There was actually no bug in my PERL script, really. It turned out that the penetrating acronyms were due to inappropriate mixing of different extended Hubble schemes in the original catalog!

That was too much even for PERL

Thanks again for your help,
Bye Fridger