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We present the first edition of a catalog of variable stars found in the Magellanic Clouds using OGLE-II data obtained during four years: 1997-2000. The catalog covers about 7 square degrees of the sky - 21 fields in the Large Magellanic…

We present results of star variability analysis in OGLE II first bulge field. Photometric database was derived by means of image subtraction method (Wozniak 2000) and contains 4597 objects pre-classified as variables. We analyzed all the…

Astrophysics · Physics 2007-05-23 Tomasz Mizerski , Michal Bejger

We present an updated collection of eclipsing and ellipsoidal binary systems in the Large and Small Magellanic Clouds (LMC and SMC), as observed by the Optical Gravitational Lensing Experiment (OGLE) survey. The catalog comprises a total of…

We present 97 QSO candidates in 48 Galactic Bulge fields of the Optical Gravitational Lensing Experiment II (OGLE-II) covering about 11 square degrees, which are selected via their variability. We extend light curves of variable objects…

Within the last years, the classification of variable stars with Machine Learning has become a mainstream area of research. Recently, visualization of time series is attracting more attention in data science as a tool to visually help…

Instrumentation and Methods for Astrophysics · Physics 2019-03-13 Christian Pieringer , Karim Pichara , Márcio Catelán , Pavlos Protopapas

The fourteenth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) contains Cepheid variables detected in the OGLE-II and OGLE-III fields toward the Galactic bulge. The catalog is divided into two main categories: 32 classical…

Solar and Stellar Astrophysics · Physics 2012-01-04 I. Soszynski , A. Udalski , P. Pietrukowicz , M. K. Szymanski , M. Kubiak , G. Pietrzynski , L. Wyrzykowski , K. Ulaczyk , R. Poleski , S. Kozlowski

We describe the Difference Image Analysis (DIA) algorithms and software used to analyze four years (1997-2000) of OGLE-II photometric monitoring of the Magellanic Clouds, the calibration, the photometric error analysis, and the search for…

Astrophysics · Physics 2007-05-23 K. Zebrun , I. Soszynski , P. R. Wozniak

The success of automatic classification of variable stars strongly depends on the lightcurve representation. Usually, lightcurves are represented as a vector of many statistical descriptors designed by astronomers called features. These…

Solar and Stellar Astrophysics · Physics 2016-04-13 Cristóbal Mackenzie , Karim Pichara , Pavlos Protopapas

Variable stars play a key role in understanding the Milky Way and the universe. The era of astronomical big data presents new challenges for quick identification of interesting and important variable stars. Accurately estimating the periods…

Instrumentation and Methods for Astrophysics · Physics 2022-12-21 Xiao-Hui Xu , Qing-Feng Zhu , Xu-Zhi Li , Bin Li , Hang Zheng , Jin-Sheng Qiu , Hai-Bin Zhao

We present a sample of 209 variable objects - very likely optical counterparts to the X-ray sources detected in the direction of the Galactic center by the Galactic Bulge Survey (GBS) carried out with the Chandra satellite. The variable…

We present a methodology to discover outliers in catalogs of periodic light-curves. We use cross-correlation as measure of ``similarity'' between two individual light-curves and then classify light-curves with lowest average ``similarity''…

Astrophysics · Physics 2009-11-11 P. Protopapas , J. M. Giammarco , L. Faccioli , M. F. Struble , R. Dave , C. Alcock

We present the discovery and statistical analysis of $12\;660$ spotted variable stars toward and inside the Galactic bulge from over two-decade-long Optical Gravitational Lensing Experiment (OGLE) data. We devise a new method of dereddening…

Despite the great promise of machine-learning algorithms to classify and predict astrophysical parameters for the vast numbers of astrophysical sources and transients observed in large-scale surveys, the peculiarities of the training data…

Instrumentation and Methods for Astrophysics · Physics 2015-05-28 Joseph W. Richards , Dan L. Starr , Henrik Brink , Adam A. Miller , Joshua S. Bloom , Nathaniel R. Butler , J. Berian James , James P. Long , John Rice

In the last years, automatic classification of variable stars has received substantial attention. Using machine learning techniques for this task has proven to be quite useful. Typically, machine learning classifiers used for this task…

Instrumentation and Methods for Astrophysics · Physics 2020-01-08 Lukas Zorich , Karim Pichara , Pavlos Protopapas

We proposed a machine learning approach to identify and distinguish dusty stellar sources employing supervised and unsupervised methods and categorizing point sources, mainly evolved stars, using photometric and spectroscopic data collected…

We present new version of the OGLE-II catalog of eclipsing binary stars detected in the Small Magellanic Cloud, based on Difference Image Analysis catalog of variable stars in the Magellanic Clouds containing data collected from 1997 to…

We present analysis of the large sample of variable red giants from the Large and Small Magellanic Clouds detected during the second phase of the Optical Gravitational Lensing Experiment (OGLE-II) and supplemented with OGLE-III photometry.…

Recently the OGLE experiment has provided accurate light curves and colours for about 2 millions stars in the Small Magellanic Cloud. We have examined this database for its content of Be stars, applying some selection criteria, and we have…

Astrophysics · Physics 2009-11-07 R. E. Mennickent , G. Pietrzynski , W. Gieren , O. Szewczyk

We present a collection of 65,981 Mira-type variable stars found in the Optical Gravitational Lensing Experiment (OGLE) project database. Two-thirds of our sample (40,356 objects) are located in the Galactic bulge fields, whereas 25,625…

We present a collection of 450 598 eclipsing and ellipsoidal binary systems detected in the OGLE fields toward the Galactic bulge. The collection consists of binary systems of all types: detached, semi-detached, and contact eclipsing…