# numerical galaxy morphology classification scheme

For an assignment, I've been told to divide up the galaxies with a Virgo Cluster Catalog number into early and late-type galaxies using the GOLDMine database, http://goldmine.mib.infn.it:8080/

Accessing the data required for analysis is not a problem,

(Search by Parameters -> (Tick VIRGO cluster) QueryGOLDMine -> (Tick Type) Get output)

but I do not understand what the numbers listed for the galaxy type mean.

I originally thought they represented a galaxy's Numerical Hubble stage, but then realized the data contains numbers outside of the Hubble stage. (E.g 20 for VCC0003.)

What morphological classification scheme is the database using?

In the search by parameters screen you'll notice you can set limits on the morphological type. The types are given names, but the limits are input as though they are ordered. A little experimenting confirms the numbers you see reported as "type" correspond to the limits options, in the order of the drop-down menu. That is, we have:

-3: dS0           5: Sb           13: Pec
-2: dE/dS0        6: Sbc          14: S/BCD
-1: dE            7: Sc           15: Sm/BCD
0: E-E/S0        8: Scd          16: Im/BCD
1: S0            9: Sd           17: BCD
2: S0a-S0/Sa    10: Sdm-Sd/Sm    18: S(dS)
3: Sa           11: Sm           19: dIm/dE
4: Sab          12: Im           20: ?


No these are not standard numbers, and no it doesn't really make sense to limit queries with these as though they form a strict, well-ordered sequence (perhaps you want S0 and Pec but nothing in between).