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January - June 2012

Automatic detection of peculiar galaxies in large datasets of galaxy images

Lior Shamir

We propose an image analysis unsupervised learning algorithm that can detect peculiar galaxies in datasets of galaxy images. The algorithm first computes a large set of calculated characteristics reflecting different aspects of the visual content, a ...
A Revised Parallel-sequence Morphological Classification of Galaxies: Structure and Formation of S0 and Spheroidal Galaxies

Kormendy, John; Bender, Ralf

We update van den Bergh's parallel-sequence galaxy classification in which S0 galaxies form a sequence S0a-S0b-S0c that parallels the sequence Sa-Sb-Sc of spiral galaxies. The ratio B/T of bulge-to-total light defines the position of a galaxy in thi ...
NEOWISE Studies of Asteroids with Sloan Photometry: Preliminary Results

Mainzer, A.; Masiero, J.; Grav, T.; Bauer, J.; Tholen, D. J.; McMillan, R. S.; Wright, E.; Spahr, T.; Cutri, R. M.; Walker, R.; Mo, W.; Watkins, J.; Hand, E.; Maleszewski, C.

We have combined the NEOWISE and Sloan Digital Sky Survey data to study the albedos of 24,353 asteroids with candidate taxonomic classifications derived using Sloan photometry. We find a wide range of moderate to high albedos for candidate S-type as ...
Dependence of Barred Galaxy Fraction on Galaxy Properties and Environment

Lee, Gwang-Ho; Park, Changbom; Lee, Myung Gyoon; Choi, Yun-Young

We investigate the dependence of the occurrence of bars in galaxies on galaxy properties and environment. We use a volume-limited sample of 33,391 galaxies brighter than Mr = -19.5 + 5logh at 0.02 <= z <= 0.05489, drawn from the Sloan Digital Sky Su ...
The Active Asteroids

Jewitt, David

Some asteroids eject dust, unexpectedly producing transient, comet-like comae and tails. First ascribed to the sublimation of near-surface water ice, mass-losing asteroids (also called "main-belt comets") can in fact be driven by a surprising divers ...
The DEEP2 Galaxy Redshift Survey: The Voronoi-Delaunay Method Catalog of Galaxy Groups

Gerke, Brian F.; Newman, Jeffrey A.; Davis, Marc; Coil, Alison L.; Cooper, Michael C.; Dutton, Aaron A.; Faber, S. M.; Guhathakurta, Puragra; Konidaris, Nicholas; Koo, David C.; Lin, Lihwai; Noeske, Kai; Phillips, Andrew C.; Rosario, David J.; Weiner, Benjamin J.; Willmer, Christopher N. A.; Yan, Renbin

We present a public catalog of galaxy groups constructed from the spectroscopic sample of galaxies in the fourth data release from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Galaxy Redshift Survey, including the Extended Groth Strip (EGS). ...
Exploring the Morphology of RAVE Stellar Spectra

Matijevič, G.; Zwitter, T.; Bienaymé, O.; Bland-Hawthorn, J.; Boeche, C.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Munari, U.; Navarro, J.; Parker, Q. A.; Reid, W.; Seabroke, G.; Siebert, A.; Siviero, A.; Steinmetz, M.; Watson, F. G.; Williams, M.; Wyse, R. F. G.

The RAdial Velocity Experiment (RAVE) is a medium-resolution (R ~ 7500) spectroscopic survey of the Milky Way that has already obtained over half a million stellar spectra. They present a randomly selected magnitude-limited sample, so it is importan ...
When time matters

Pourbaix, D.

Whereas deriving the orbit of a binary star was perceived as a tedious task even during the second half of the 20th century, nowadays, computers can investigate millions of solutions and keep the best one in just a few seconds. However, even if one ...
Gravitational-Wave Data Analysis. Formalism and Sample Applications: The Gaussian Case

Jaranowski, Piotr; Królak, Andrzej

The article reviews the statistical theory of signal detection in application to analysis of deterministic gravitational-wave signals in the noise of a detector. Statistical foundations for the theory of signal detection and parameter estimation are ...
Bayesian non-parametrics and the probabilistic approach to modelling

Zoubin Ghahramani

Modelling is fundamental to many fields of science and engineering. A model can be thought of as a representation of possible data one could predict from a system. The probabilistic approach to modelling uses probability theory to express all aspect ...
Gaussian processes for time-series modelling

S. Roberts, M. Osborne, M. Ebden, S. Reece, N. Gibson and S. Aigrain

In this paper, we offer a gentle introduction to Gaussian processes for time-series data analysis. The conceptual framework of Bayesian modelling for time-series data is discussed and the foundations of Bayesian non-parametric modelling presented fo ...
Independent component analysis: recent advances

Aapo Hyvärinen

Independent component analysis is a probabilistic method for learning a linear transform of a random vector. The goal is to find components that are maximally independent and non-Gaussian (non-normal). Its fundamental difference to classical multi-v ...
Similarity and denoising

Paul M. B. Vitányi

We can discover the effective similarity among pairs of finite objects and denoise a finite object using the Kolmogorov complexity of these objects. The drawback is that the Kolmogorov complexity is not computable. If we approximate it, using a good ...
Plain fundamentals of Fundamental Planes: analytics and algorithms

Sheth, Ravi K.; Bernardi, Mariangela

Estimates of the coefficients a and b of the Fundamental Plane relation R∝σa Ib depend on whether one minimizes the scatter in the R direction, or orthogonal to the plane. We provide explicit expressions for a and b (and confidence limits) in ter ...
Computer Vision for the Solar Dynamics Observatory (SDO)

Martens, P. C. H.; Attrill, G. D. R.; Davey, A. R.; Engell, A.; Farid, S.; Grigis, P. C.; Kasper, J.; Korreck, K.; Saar, S. H.; Savcheva, A.; Su, Y.; Testa, P.; Wills-Davey, M.; Bernasconi, P. N.; Raouafi, N.-E.; Delouille, V. A.; Hochedez, J. F.; Cirtain, J. W.; Deforest, C. E.; Angryk, R. A.; de Moortel, I.; Wiegelmann, T.; Georgoulis, M. K.; McAteer, R. T. J.; Timmons, R. P.

In Fall 2008 NASA selected a large international consortium to produce a comprehensive automated feature-recognition system for the Solar Dynamics Observatory (SDO). The SDO data that we consider are all of the Atmospheric Imaging Assembly (AIA) ima ...
A blind detection of a large, complex, Sunyaev-Zel'dovich structure

AMI Consortium; Shimwell, T. W.; Barker, R. W.; Biddulph, P.; Bly, D.; Boysen, R. C.; Brown, A. R.; Brown, M. L.; Clementson, C.; Crofts, M.; Culverhouse, T. L.; Czeres, J.; Dace, R. J.; Davies, M. L.; D'Alessandro, R.; Doherty, P.; Duggan, K.; Ely, J. A.; Felvus, M.; Feroz, F.; Flynn, W.; Franzen, T. M. O.; Geisbüsch, J.; Génova-Santos, R.; Grainge, K. J. B.; Grainger, W. F.; Hammett, D.; Hobson, M. P.; Holler, C. M.; Hurley-Walker, N.; Jilley, R.; Kaneko, T.; Kneissl, R.; Lancaster, K.; Lasenby, A. N.; Marshall, P. J.; Newton, F.; Norris, O.; Northrop, I.; Odell, D. M.; Olamaie, M.; Perrott, Y. C.; Pober, J. C.; Pooley, G. G.; Pospieszalski, M. W.; Quy, V.; Rodríguez-Gonzálvez, C.; Saunders, R. D. E.; Scaife, A. M. M.; Schammel, M. P.; Schofield, J.; Scott, P. F.; Shaw, C.; Smith, H.; Titterington, D. J.; Velić, M.; Waldram, E. M.; West, S.; Wood, B. A.; Yassin, G.; Zwart, J. T. L.

We present an interesting Sunyaev-Zel’dovich (SZ) detection in the first of the Arcminute Microkelvin Imager (AMI) ‘blind’, degree-square fields to have been observed down to our target sensitivity of ?. In follow-up deep pointed observations ...
Parametrization effects in the analysis of AMI Sunyaev-Zel'dovich observations

AMI Consortium; Olamaie, Malak; Rodríguez-Gonzálvez, Carmen; Davies, Matthew L.; Feroz, Farhan; Franzen, Thomas M. O.; Grainge, Keith J. B.; Hobson, Michael P.; Hurley-Walker, Natasha; Lasenby, Anthony N.; Pooley, Guy G.; Saunders, Richard D. E.; Scaife, Anna M. M.; Schammel, Michel; Scott, Paul F.; Shimwell, Timothy W.; Titterington, David J.; Waldram, Elizabeth M.; Zwart, Jonathan T. L.

Most Sunyaev-Zel'dovich (SZ) and X-ray analyses of galaxy clusters try to constrain the cluster total mass (MT(r)) and/or gas mass (Mg(r)) using parametrized models derived from both simulations and imaging observations, and assumptions of spherical ...
Principles of high-dimensional data visualization in astronomy

Goodman, A. A.

Astronomical researchers often think of analysis and visualization as separate tasks. In the case of high-dimensional data sets, though, interactive exploratory data visualization can give far more insight than an approach where data processing and ...
Distinguishing between a true period and its alias, and other tasks of model discrimination

Baluev, Roman V.

We consider the task of distinguishing between two different alternative models that can explain observed time-series data roughly equally, mainly focusing on the period-ambiguity case (aliasing). We propose a test for checking whether the rival mod ...
How well do STARLAB and NBODY compare? II. Hardware and accuracy

Anders, P.; Baumgardt, H.; Gaburov, E.; Portegies Zwart, S.

Most recent progress in understanding the dynamical evolution of star clusters relies on direct N-body simulations. Owing to the computational demands, and the desire to model more complex and more massive star clusters, hardware calculational accel ...
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