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We present the results of a programme to search and identify the nature of unusual sources within the All-sky Wide-field Infrared Survey Explorer (WISE) that is based on a machine-learning algorithm for anomaly detection, namely one-class…

Lensed quasars are key to many areas of study in astronomy, offering a unique probe into the intermediate and far universe. However, finding lensed quasars has proved difficult despite significant efforts from large collaborations. These…

We derive stellar parameters and abundances (`stellar labels') of 40,034 late-B and A-type main-sequence stars extracted from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope Medium Resolution Survey (LAMOST--MRS). The primary…

Solar and Stellar Astrophysics · Physics 2021-11-17 Weijia Sun , Xiao-Wei Duan , Licai Deng , Richard de Grijs , Bo Zhang , Chao Liu

The main purpose of this article is to alert spectroscopists, particularly those involved in surveys, to the fact that rapidly pulsating sources induce periodic structures in spectra. This would allow the detection of new classes of objects…

High Energy Astrophysical Phenomena · Physics 2010-03-18 Ermanno F. Borra

LAMOST-MRS-B is one of the sub-surveys of LAMOST medium-resolution (R~7500) spectroscopic survey. It aims at studying the statistical properties (e.g., binary fraction, orbital period distribution, mass ratio distribution) of binary stars…

The emission of very-high-energy photons (VHE, E>100 GeV$) in blazars is closely connected to the production of ultra-relativistic particles and the role of these gamma-ray sources as cosmic particle accelerators. This work focuses on a…

High Energy Astrophysical Phenomena · Physics 2022-03-04 M. Nievas Rosillo , A. Domínguez , G. Chiaro , G. La Mura , A. Brill , V. S. Paliya

The study of machine learning (ML) techniques for the autonomous classification of astrophysical sources is of great interest, and we explore its applications in the context of a multifrequency data-frame. We test the use of supervised ML…

High Energy Astrophysical Phenomena · Physics 2020-10-07 Bruno Arsioli , Pedro Dedin

Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) acquired tens of millions of low-resolution stellar spectra. The large amount of the spectra result in the urgency to explore automatic atmospheric parameter estimation…

Instrumentation and Methods for Astrophysics · Physics 2022-07-14 Xiangru Li , Si Zeng , Zhu Wang , Bing Du , Xiao Kong , Caixiu Liao

In preparation for GLAST, we have compiled a sample of blazar candidates to increase the pool of well studied AGN from which GLAST counterparts will be drawn. Sources were selected with our Figure of Merit (FoM) ranking; thus, they have…

LAMOST DR5 released more than 200,000 low resolution spectra of early-type stars with S/N>50. Searching for metallic-line (Am) stars in such a large database and study of their statistical properties are presented in this paper. Six machine…

Solar and Stellar Astrophysics · Physics 2019-06-05 Li Qin , A-Li Luo , Wen Hou , Yin-Bi Li , Shuo Zhang , Rui Wang , Li-Li Wang , Xiao Kong , Jin-Shu Han

Active Galaxies with a jet pointing towards us, so-called blazars, play an important role in the field of high-energy astrophysics. One of the most important features in the classification scheme of blazars is the peak frequency of the…

High Energy Astrophysical Phenomena · Physics 2022-07-11 Theo Glauch , Tobias Kerscher , Paolo Giommi

Blazars are a highly-variable, radio-loud subclass of active galactic nuclei (AGN). In order to better understand such objects we must be able to easily identify candidate blazars from the growing population of unidentified sources. Working…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Philip S. Cowperthwaite , F. Massaro , R. D'Abrusco , A. Paggi , G. Tosti , Howard A. Smith

Upcoming large-scale spectroscopic surveys with e.g. WEAVE and 4MOST will provide thousands of spectra of massive stars, which need to be analysed in an efficient and homogeneous way. Usually, studies of massive stars are limited to samples…

Solar and Stellar Astrophysics · Physics 2023-09-14 J. M. Bestenlehner , T. Enßlin , M. Bergemann , P. A. Crowther , M. Greiner , M. Selig

Forthcoming surveys such as the Large Synoptic Survey Telescope (LSST) and Euclid necessitate automatic and efficient identification methods of strong lensing systems. We present a strong lensing identification approach that utilizes a…

Instrumentation and Methods for Astrophysics · Physics 2019-08-29 Camille Avestruz , Nan Li , Hanjue Zhu , Matthew Lightman , Thomas E. Collett , Wentao Luo

In this work, we present a catalog of cataclysmic variables (CVs) identified from the Sixth Data Release (DR6) of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). To single out the CV spectra, we introduce a novel…

We present BeppoSAX LECS, MECS, and PDS spectra of eleven X-ray selected BL Lacertae objects. Combining these sources with the ones presented elsewhere we have a sample of 21 BL Lacs from the Einstein Medium Sensitivity and Einstein Slew…

Astrophysics · Physics 2009-11-07 V. Beckmann , A. Wolter , A. Celotti , L. Costamante , G. Ghisellini , T. Maccacaro , G. Tagliaferri

LAMOST (Large sky Area Multi-Object fiber Spectroscopic Telescope) is a Chinese national scientific research facility operated by National Astronomical Observatories, Chinese Academy of Sciences (NAOC). After two years of commissioning…

Instrumentation and Methods for Astrophysics · Physics 2012-06-19 Gang Zhao , Yongheng Zhao , Yaoquan Chu , Yipeng Jing , Licai Deng

Detecting rare objects from a few examples is an emerging problem. Prior works show meta-learning is a promising approach. But, fine-tuning techniques have drawn scant attention. We find that fine-tuning only the last layer of existing…

Computer Vision and Pattern Recognition · Computer Science 2020-03-17 Xin Wang , Thomas E. Huang , Trevor Darrell , Joseph E. Gonzalez , Fisher Yu

We have performed intermediate resolution (R = 5000), high signal-to-noise H-band spectroscopy of a small, initial sample of three massive embedded young stellar objects (YSOs), using VLT/ISAAC. The sample has been selected from sources…

Astrophysics · Physics 2016-08-30 T. R. Kendall , W. J. de Wit , J. L. Yun