|Compilation of morphology of galaxies|
The morphological information derived from the combination of the various estimates for a given galaxy is presented in the homogenized catalogue (fields t and type). The morphological type is used for computing several other astrophysical parameters, in particular for estimating geometric and photometric corrections which depends on the SED and intrinsic shape.
For more details about the classification of galaxies read the article Qualitative classification of galaxies, alternate systems and modifications from the NED knowledge database (Level 5).
Beside references providing a detailed classifications, the compilation includes approximates descriptions (typically differentiating elliptical and spiral galaxies; E/S). These descriptions are given the 'quality' code 3. Indirect estimates of the type are also compiled, like those derived from the shape of the photometric profiles (quality=2; for 2MASS, ref=27129, the type was computed from the concentration index as: t=10-2*concent). (To compute the homogenized classification, these crude estimates are naturally used only if no detailed description is available).
The reference system of the morphological classification is the RC3 (reference code=4008) which provide 18883 morphological descriptions. The main references are listed below:
Below is a description of the fields of the table that can be accessed through the interfaces.
|0|| no bar is mentioned
|0|| no ring is mentioned
|2||very compact galaxy|
|3||extremely compact galaxy|
|5||very diffuse galaxy|
|6||extremely diffuse galaxy|
|2||Strong interaction in the center of a cluster (cD galaxy)|
|9||superimposed star mentioned|
|0||accurate detailed classification|
|1||detailed classification of lower accuracy
|2||derived from photometric profile
|9||measurement to be rejected|