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This paper presents an automated classification algorithm designed for analyzing multi-wavelength astronomical data. Addressing the challenge of data avalanche in astronomy, it employs data mining and knowledge discovery techniques to improve classification efficiency and accuracy. The Naïve Bayes classifier is utilized to handle high-dimensional data, featuring a comprehensive approach that includes data cleaning, feature selection, and validation. The algorithm is applicable to various data types, including optical and infrared, and serves as a powerful tool for source candidate preselection in large surveys.
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LAMOST An Automated Classification Algorithm for Multi-wavelength Data Yanxia Zhang, Ali Luo,Yongheng Zhao National Astronomical Observatories, China 2005.8.16, Lijiang
ROSAT ~keV DSS Optical IRAS 25m 2MASS 2m GB 6cm WENSS 92cm NVSS 20cm IRAS 100m Astronomy facing “data avalanche”
Necessity Necessity Is the Mother of Invention Data avalanche Virtual Observatories DM & KDD
Data Mining & KDD Knowledge Pattern evaluation • DM—core of KDD DM task selection Data warehouse Data cleaning Data federation Database
One Task of DM:Classification The scheme of classification of multiwavelength data Training set Classification method Feature selection Selected features Test set classifier Validated set predict all features New data Cross identification
Data sample Near infrared 2MASS J,H,K optical USNO A2.0 B,R X ray ROSAT CR,HR1,HR2, ext,extl
Known sample star SIMBAD Normal galaxies RC3 AGNs Veron(2000)
Feature Selection Parameters:B+2.5lgCR,J+2.5lgCR,B-R,J-H,H-K,lgCR, HR1,HR2,ext,extl Methods: ReliefF Result of feature selection:
Classification Method: Naïve Bayes classifier Classification results for three situations
Summary 1. By feature selection, we can deal with high dimensional data, and select important attributes, thus improve the efficiency and effect of classification. 2. The Naïve Bayes algorithm is an robust method to classify multiwavelength data with high accuracy of classification. It is not only used for multiwavelength data, but also for other data, such as photometric data, spectra data, image data or the combined data of these types of data. 3. With the classifier, it is helpful to preselect source candidates for large surveys and classify the new data. 4. The methods will be part of VO toolkits.