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The Apache Point Observatory Galactic Evolution Experiment (APOGEE), part of the Sloan Digital Sky Survey III, explores the stellar populations of the Milky Way using the Sloan 2.5-m telescope linked to a high resolution (R~22,500),…

In this work we apply and expand on a recently introduced outlier detection algorithm that is based on an unsupervised random forest. We use the algorithm to calculate a similarity measure for stellar spectra from the Apache Point…

Instrumentation and Methods for Astrophysics · Physics 2018-05-29 Itamar Reis , Dovi Poznanski , Dalya Baron , Gail Zasowski , Sahar Shahaf

APOGEE is a large-scale, NIR, high-resolution (R~20,000) spectroscopic survey of Galactic stars. It is one of the four experiments in SDSS-III. Because APOGEE will observe in the H band, it will be the first survey to pierce through…

The Apache Point Observatory Galactic Evolution Experiment (APOGEE), one of the programs in the Sloan Digital Sky Survey III (SDSS-III), has now completed its systematic, homogeneous spectroscopic survey sampling all major populations of…

Instrumentation and Methods for Astrophysics · Physics 2017-09-06 Steven R. Majewski , Ricardo P. Schiavon , Peter M. Frinchaboy , Carlos Allende Prieto , Robert Barkhouser , Dmitry Bizyaev , Basil Blank , Sophia Brunner , Adam Burton , Ricardo Carrera , S. Drew Chojnowski , Katia Cunha , Courtney Epstein , Greg Fitzgerald , Ana E. Garcia Perez , Fred R. Hearty , Chuck Henderson , Jon A. Holtzman , Jennifer A. Johnson , Charles R. Lam , James E. Lawler , Paul Maseman , Szabolcs Meszaros , Matthew Nelson , Duy Coung Nguyen , David L. Nidever , Marc Pinsonneault , Matthew Shetrone , Stephen Smee , Verne V. Smith , Todd Stolberg , Michael F. Skrutskie , Eric Walker , John C. Wilson , Gail Zasowski , Friedrich Anders , Sarbani Basu , Stephane Beland , Michael R. Blanton , Jo Bovy , Joel R. Brownstein , Joleen Carlberg , William Chaplin , Cristina Chiappini , Daniel J. Eisenstein , Yvonne Elsworth , Diane Feuillet , Scott W. Fleming , Jessica Galbraith-Frew , Rafael A. Garcia , D. Anibal Garcia-Hernandez , Bruce A. Gillespie , Leo Girardi , James E. Gunn , Sten Hasselquist , Michael R. Hayden , Saskia Hekker , Inese Ivans , Karen Kinemuchi , Mark Klaene , Suvrath Mahadevan , Savita Mathur , Benoit Mosser , Demitri Muna , Jeffrey A. Munn , Robert C. Nichol , Robert W. O'Connell , A. C. Robin , Helio Rocha-Pinto , Matthias Schultheis , Aldo M. Serenelli , Neville Shane , Victor Silva Aguirre , Jennifer S. Sobeck , Benjamin Thompson , Nicholas W. Troup , David H. Weinberg , Olga Zamora

(Abridged) This paper explores the use of k-means clustering as a tool for automated unsupervised classification of massive stellar spectral catalogs. The classification criteria are defined by the data and the algorithm, with no prior…

Solar and Stellar Astrophysics · Physics 2015-06-12 J. Sanchez Almeida , C. Allende Prieto

Machine learning allows efficient extraction of physical properties from stellar spectra that have been obtained by large surveys. The viability of ML approaches has been demonstrated for spectra covering a variety of wavelengths and…

We describe the design and performance of the near-infrared (1.51--1.70 micron), fiber-fed, multi-object (300 fibers), high resolution (R = lambda/delta lambda ~ 22,500) spectrograph built for the Apache Point Observatory Galactic Evolution…

Many field stars reside in binaries, and the analysis and interpretation of photometric and spectroscopic surveys must take this into account. We have developed a model to predict how binaries influence the scientific results inferred from…

Solar and Stellar Astrophysics · Physics 2018-04-26 Edita Stonkutė , Ross P. Church , Sofia Feltzing , Jennifer A. Johnson

In addition to comprehensive surveys of the Milky Way bulge, disk, and halo, the Apache Point Galactic Evolution Experiment (APOGEE) project observed seven dwarf spheroidal satellites (dSphs) of the Milky Way: Carina, Sextans, Sculptor,…

We train a convolutional neural network, APOGEE Net, to predict $T_\mathrm{eff}$, $\log g$, and, for some stars, [Fe/H], based on the APOGEE spectra. This is the first pipeline adapted for these data that is capable of estimating these…

The Sloan Digital Sky Survey III/Apache Point Observatory Galactic Evolution Experiment (SDSS-III/APOGEE) is a large-scale spectroscopic survey of Galactic stars and star clusters. The SDSS-III/APOGEE survey is designed to produce high-S/N,…

Using the 'k-means' cluster analysis algorithm, we carry out an unsupervised classification of all galaxy spectra in the seventh and final Sloan Digital Sky Survey data release (SDSS/DR7). Except for the shift to restframe wavelengths, and…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-16 J. Sanchez Almeida , J. A. L. Aguerri , C. Munoz-Tunon , A. de Vicente

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) - one of the Sloan Digital Sky Survey III programs -- is using near-infrared spectra of $\sim 100,000$ red giant branch star candidates to study the structure of the Milky…

Deep learning with artificial neural networks is increasingly gaining attention, because of its potential for data-driven astronomy. However, this methodology usually does not provide uncertainties and does not deal with incompleteness and…

Astrophysics of Galaxies · Physics 2019-01-11 Henry W. Leung , Jo Bovy

(abridged) We develop a tool for the automated spectral classification of OB stars according to their sub-types. We use the regular Random Forest (RF) algorithm, the Probabilistic RF (PRF), and we introduce the KDE-RF method which is a…

Solar and Stellar Astrophysics · Physics 2022-01-12 E. Kyritsis , G. Maravelias , A. Zezas , P. Bonfini , K. Kovlakas , P. Reig

In single-particle cryo-electron microscopy (cryo-EM), K-means clustering algorithm is widely used in unsupervised 2D classification of projection images of biological macromolecules. 3D ab initio reconstruction requires accurate…

Quantitative Methods · Quantitative Biology 2017-01-03 Yaofang Xu , Jiayi Wu , Chang-Cheng Yin , Youdong Mao

Large-scale spectroscopic surveys have collectively observed millions of stars across the Milky Way, but each derives stellar labels using independent pipelines with distinct modelling assumptions, introducing systematic offsets that…

Astrophysics of Galaxies · Physics 2026-04-29 Jeff Shen , Joshua S. Speagle , Shirley Ho

The Sloan Digital Sky Survey--III (SDSS--III) Apache Point Observatory Galactic Evolution Experiment (APOGEE) has obtained high resolution (R $\sim$ 22,500), high signal-to-noise ratio ($>$ 100) spectra in the H$-$band ($\sim$1.5$-$1.7…

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