Identification of outliers through clustering and semi-supervised learning for all sky surveys

Sharmodeep Bhattacharyya, Joseph W. Richards, John Rice, Dan L. Starr, Nathaniel R. Butler, Joshua S. Bloom

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Recently there has been a huge surge of data in astronomy, making outlier or novelty detection a crucial step in analyzing these data. Here, we introduce a clustering based semi-supervised approach for outlier detection. The training data, (X1,Y1), . . . , (Xn,Yn), where n = 1,542, comes from Hipparcos and Optical Gravitational Lensing Experiment (OGLE) surveys, with, Xi ∈ Rp (p = 64) as the features and Yi is a categorical variable having one of the 25 class labels. The set of 64 periodic and non-periodic features are extracted from the light curves. The test data, Z1, . . . ,Zm, where m = 11,375, is the test data, where, Zi ∈ Rp.We select these 11,375 low noise variable light sources for our analysis from a set of unlabeled light curves of ∼50,000 variable light sources from All Sky Automated Survey (ASAS). Our goal is to find outlier data points in the unlabeled data set whose labels can not be properly predicted by the information in the labeled data set. We propose a new hierarchical algorithm for outlier detection in this partially labeled setup based on clustering and semi-supervised learning.We apply our method to identify interesting sources in the ASAS data set, with the training data. We present the ASAS light curves of some of these interesting sources, and elaborate on the possible physical mechanisms driving their variability.

Original languageEnglish (US)
Title of host publicationStatistical Challenges in Modern Astronomy V
PublisherSpringer Science and Business Media, LLC
Number of pages3
ISBN (Print)9781461435198
StatePublished - 2012
Externally publishedYes
Event5th Statistical Challenges in Modern Astronomy Symposium, SCMA 2011 - University Park, PA, United States
Duration: Jun 13 2011Jun 15 2011

Publication series

NameLecture Notes in Statistics
ISSN (Print)0930-0325
ISSN (Electronic)2197-7186


Other5th Statistical Challenges in Modern Astronomy Symposium, SCMA 2011
Country/TerritoryUnited States
CityUniversity Park, PA

ASJC Scopus subject areas

  • Statistics and Probability
  • Statistics, Probability and Uncertainty


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