J/ApJS/223/20 SDSS-DR8 galaxies classified by WND-CHARM (Kuminski+, 2016)
A computer-generated visual morphology catalog of ∼3000000 SDSS galaxies.
Kuminski E., Shamir L.
<Astrophys. J. Suppl. Ser., 223, 20-20 (2016)>
=2016ApJS..223...20K 2016ApJS..223...20K (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Morphology ; Redshifts
Keywords: catalogs; methods: data analysis; techniques: image processing
Abstract:
We have applied computer analysis to classify the broad morphological
types of ∼3x106 Sloan Digital Sky Survey (SDSS) galaxies. For each
galaxy, the catalog provides the DR8 object ID, the R.A., the decl.,
and the certainty for the automatic classification as either spiral or
elliptical. The certainty of the classification allows us to control
the accuracy of a subset of galaxies by sacrificing some of the least
certain classifications. The accuracy of the catalog was tested using
galaxies that were classified by the manually annotated Galaxy Zoo
catalog. The results show that the catalog contains ∼900000 spiral
galaxies and ∼600000 elliptical galaxies with classification certainty
that has a statistical agreement rate of ∼98% with the Galaxy Zoo
debiased "superclean" data set. The catalog also shows that objects
assigned by the SDSS pipeline with a relatively high redshift (z>0.4)
can have clear visual spiral morphology.
Description:
The image analysis method used to classify the images is WND-CHARM
(wndchrm; Shamir et al. 2008, BMC Source Code for Biology and
Medicine, 3: 13; 2010PLSCB...6E0974S 2010PLSCB...6E0974S; 2013ascl.soft12002S), which
first computes 2885 numerical descriptors from each SDSS image such as
textures, edges, shapes), the statistical distribution of the pixel
intensities, the polynomial decomposition of the image, and fractal
features. These features are extracted from the raw pixels, as well as
the image transforms and multi-order image transforms. See section 2
for further explanations.
In a similar way than the catalog we also compiled a catalog of all
objects with spectra in DR8. For each object, that catalog contains
the spec ObjID, the R.A., the decl., the z, z error, the certainty of
classification as elliptical, the certainty of classification as
spiral, and the certainty of classification as a star. See section 3.1
for further explanations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 90 2912341 Catalog of broad morphology of SDSS galaxies
spec.dat 147 2638883 Morphological catalog of SDSS objects with spectra
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See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
J/MNRAS/435/2835 : Morphological types from Galaxy Zoo 2 (Willett+, 2013)
J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)
J/A+A/532/A74 : EFIGI catalog of 4458 nearby galaxies (de Lapparent+, 2011)
J/MNRAS/412/727 : SDSS red gal. automated morph. classification (Cheng+, 2011)
J/MNRAS/410/166 : Morphological types from Galaxy Zoo 1 (Lintott+, 2011)
J/A+A/525/A157 : SDSS automated morphology classif. (Huertas-Company+, 2011)
J/ApJS/186/427 : Detailed morphology of SDSS galaxies (Nair+, 2010)
J/ApJS/147/1 : Classification of nearby galaxies (Conselice+, 2003)
J/ApJ/588/218 : i*g* photometry of SDSS EDR galaxies (Abraham+, 2003)
http://www.sdss.org/ : SDSS home page
http://vfacstaff.ltu.edu/lshamir/downloads/ImageClassifier/ :
WND-CHARM algorithm
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- objID SDSS-DR8 object identifier
21- 42 F22.18 deg RAdeg [0/360] Right ascension in decimal degrees (J2000)
44- 64 E21.18 deg DEdeg [-25/85] Declination in decimal degrees (J2000)
66- 77 E12.10 --- Ell [0/1] Certainty of the galaxy being elliptical
79- 90 E12.10 --- S [0/1] Certainty of the galaxy being spiral
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Byte-by-byte Description of file: spec.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- objID SDSS object ID
21- 39 I19 --- SpID SDSS spectrum ID (SpecObjid)
41- 53 F13.9 deg RAdeg Right ascension in decimal degrees (J2000)
55- 69 F15.11 deg DEdeg Declination in decimal degrees (J2000)
71- 88 F18.15 --- z [-0.02/7.1]?=0 Spectroscopic redshift
90-109 F20.14 --- e_z [-6/30689]?=0 z uncertainty
111-118 F8.6 --- Ell [0/1] Certainty of the galaxy being elliptical
120-127 F8.6 --- S [0/1] Certainty of the galaxy being spiral
129-136 F8.6 --- Star [0/1] Certainty of the galaxy being a star
138-147 A10 --- Class Classification ("Elliptical", "Spiral" or "Star")
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History:
Downloaded at: http://vfacstaff.ltu.edu/lshamir/data/morph_catalog/
(wndchrmcatalogn.csv.gz file from 2016 Feb 19;
and wndchrmspeccatalog.csv.gz)
(End) Emmanuelle Perret [CDS] 16-Jun-2016