Astroimagej: image processing and photometric extraction for ultra-precise astronomical light curves

Karen A. Collins,

Karen A. Collins

Department of Physics & Astronomy, Vanderbilt University, Nashville, TN 37235, USA; [email protected]; Department of Physics, …

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John F. Kielkopf,

John F. Kielkopf

Department of Physics & Astronomy, University of Louisville, Louisville, KY 40292, USA

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Keivan G. Stassun,

Keivan G. Stassun

Department of Physics & Astronomy, Vanderbilt University, Nashville, TN 37235, USA; [email protected]; Department of Physics, …

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Frederic V. Hessman

Frederic V. Hessman

Inst. f. Astrophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

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Published: Jan. 1, 2017

ImageJ is a graphical user interface (GUI) driven, public domain, Java-based, software package for general image processing traditionally used mainly in life sciences fields. The image processing capabilities of ImageJ are useful and extendable to other scientific fields. Here we present AstroImageJ (AIJ), which provides an astronomy specific image display environment and tools for astronomy specific image calibration and data reduction. Although AIJ maintains the general purpose image processing capabilities of ImageJ, AIJ is streamlined for time-series differential photometry, light curve detrending and fitting, and light curve plotting, especially for applications requiring ultra-precise light curves (e.g., exoplanet transits). AIJ reads …

Machine-learned Identification of RR Lyrae Stars from Sparse, Multi-band Data: The PS1 Sample

Branimir Sesar,

Branimir Sesar

Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany

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Nina Hernitschek,

Nina Hernitschek

Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany

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Sandra Mitrović,

Sandra Mitrović

Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany

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Željko Ivezić,

Željko Ivezić

University of Washington, Department of Astronomy, P.O.Box 351580, Seattle, WA 98195-1580, USA; [email protected]

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Hans-Walter Rix,

Hans-Walter Rix

Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany

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Judith G. Cohen,

Judith G. Cohen

Division of Physics, Mathematics and Astronomy, Caltech, Pasadena, CA 91125, USA

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Edouard J. Bernard,

Edouard J. Bernard

Université Côte d’Azur, OCA, CNRS, Lagrange, France

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Eva K. Grebel,

Eva K. Grebel

Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12–14, D-69120 Heidelberg, Germany

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Nicolas F. Martin,

Nicolas F. Martin

Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany; Observatoire astronomique de Strasbourg, Université …

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Edward F. Schlafly,

Edward F. Schlafly

Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany; Lawrence Berkeley National Laboratory, One …

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William S. Burgett,

William S. Burgett

GMTO Corporation, 251 S. Lake Avenue, Suite 300, Pasadena, CA 91101, USA

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Peter W. Draper,

Peter W. Draper

Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK

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Heather Flewelling,

Heather Flewelling

Institute for Astronomy, University of Hawai’i at Manoa, Honolulu, HI 96822, USA

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Nick Kaiser,

Nick Kaiser

Institute for Astronomy, University of Hawai’i at Manoa, Honolulu, HI 96822, USA

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Rolf P. Kudritzki,

Rolf P. Kudritzki

Institute for Astronomy, University of Hawai’i at Manoa, Honolulu, HI 96822, USA

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Eugene A. Magnier,

Eugene A. Magnier

Institute for Astronomy, University of Hawai’i at Manoa, Honolulu, HI 96822, USA

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Nigel Metcalfe,

Nigel Metcalfe

Institute for Astronomy, University of Hawai’i at Manoa, Honolulu, HI 96822, USA

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John L. Tonry,

John L. Tonry

Institute for Astronomy, University of Hawai’i at Manoa, Honolulu, HI 96822, USA

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Christopher Waters

Christopher Waters

Institute for Astronomy, University of Hawai’i at Manoa, Honolulu, HI 96822, USA

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Published: May 1, 2017

RR Lyrae stars may be the best practical tracers of Galactic halo (sub-)structure and kinematics. The PanSTARRSl (PSI) Зтг survey offers multi-band, multi-epoch, precise photometry across much of the sky, but a robust identification of RR Lyrae stars in this data set poses a challenge, given PSl’s sparse, asynchronous multi-band light curves (<12 epochs in each of five bands, taken over a 4.5 year period). We present a novel template fitting technique that uses well-defined and physically motivated multi-band light curves of RR Lyrae stars, and demonstrate that we get accurate period estimates, precise to 2 s in >80% of cases. We augment these light-curve fits with other features from photometric time-series and provide them to progressively more detailed machine- learned classification models. From these models, we are able to select the widest (three-fourths of the sky) and deepest (reaching 120 kpc) sample of RR …