J/AJ/130/2439 Redshift estimates in the SDSS DR2 (Suchkov+, 2005)
A census of object types and redshift estimates in the SDSS photometric catalog
from a trained decision tree classifier.
Suchkov A.A., Hanisch R.J., Margon B.
<Astron. J., 130, 2439-2452 (2005)>
=2005AJ....130.2439S 2005AJ....130.2439S
ADC_Keywords: Galaxy catalogs ; Photometry, SDSS ; Redshifts
Keywords: astronomical data bases: miscellaneous - galaxies: active -
galaxies: distances and redshifts - quasars: general
Abstract:
We have applied ClassX, an oblique decision tree classifier optimized
for astronomical analysis, to the homogeneous multicolor imaging
database of the Sloan Digital Sky Survey (SDSS), training the software
on subsets of SDSS objects whose nature is precisely known via
spectroscopy. We find that the software, using photometric data only,
correctly classifies a very large fraction of the objects with
existing SDSS spectra, both stellar and extragalactic. ClassX also
accurately predicts the redshifts of both normal and active galaxies
in SDSS. To illustrate ClassX applications in SDSS research, we (1)
derive the object content of the SDSS Data Release 2 photometric
catalog and (2) provide a sample catalog of resolved SDSS objects that
contains a large number of candidate active galactic nucleus (AGN)
galaxies (27,000), along with 63,000 candidate normal galaxies at
magnitudes substantially fainter than the typical magnitudes of SDSS
spectroscopic objects.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 72 91847 Catalog of 91847 Galaxies and Resolved AGN from SDSS
DR2 Photometric Catalog classified with ClassX
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See also:
II/259 : The SDSS Photometric Catalog, Release 3 (Abazajian+ 2005)
http://www.sdss.org/dr2 : SDSS DR2 Home Page
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq Running number (1)
7- 15 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
17- 25 F9.5 deg DEdeg Declination in decimal degrees (J2000)
27- 31 F5.2 mag umag SDSS dereddened u band magnitude
33- 37 F5.2 mag gmag SDSS dereddened g band magnitude
39- 43 F5.2 mag rmag SDSS dereddened r band magnitude
45- 49 F5.2 mag imag SDSS dereddened i band magnitude
51- 55 F5.2 mag zmag SDSS dereddened z band magnitude
57- 60 F4.2 --- zlow Lower redshift limit
62- 65 F4.2 --- zup Upper redshift limit
67- 72 A6 --- Type Object type assigned by the classifier
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Note (1): The catalog is the result of classification of a sample of 100,000
SDSS DR2 resolved photometric objects, of which 91,847 objects were
classified as galaxies and AGN. The sample is constrained to the
"faint" magnitude range (see text for details).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 25-Aug-2006