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We present the results of various automated classification methods, based on machine learning (ML), of objects from data releases 6 and 7 (DR6 and DR7) of the Sloan Digital Sky Survey (SDSS), primarily distinguishing stars from quasars. We…

Instrumentation and Methods for Astrophysics · Physics 2018-04-16 Mohammed Viquar , Suryoday Basak , Ariruna Dasgupta , Surbhi Agrawal , Snehanshu Saha

Self-paced learning and hard example mining re-weight training instances to improve learning accuracy. This paper presents two improved alternatives based on lightweight estimates of sample uncertainty in stochastic gradient descent (SGD):…

Machine Learning · Statistics 2018-01-09 Haw-Shiuan Chang , Erik Learned-Miller , Andrew McCallum

We present a neural network based approach to the determination of photometric redshift. The method was tested on the Sloan Digital Sky Survey Early Data Release (SDSS-EDR) reaching an accuracy comparable and, in some cases, better than SED…

Estimating redshifts from broadband photometry is often limited by how accurately we can map the colors of galaxies to an underlying spectral template. Current techniques utilize spectrophotometric samples of galaxies or spectra derived…

Instrumentation and Methods for Astrophysics · Physics 2025-03-11 John Franklin Crenshaw , Andrew J. Connolly

Recent work shows that post-training datasets for LLMs can be substantially downsampled without noticeably deteriorating performance. However, data selection often incurs high computational costs or is limited to narrow domains. In this…

Computation and Language · Computer Science 2025-09-25 Paramita Mirza , Lucas Weber , Fabian Küch

In order to be efficient, spectroscopic galaxy redshift surveys do not obtain redshifts for all galaxies in the population targeted. The missing galaxies are often clustered, commonly leading to a lower proportion of successful observations…

Cosmology and Nongalactic Astrophysics · Physics 2017-09-20 Davide Bianchi , Will J. Percival

Photometric Redshift is critical for analyzing astronomical objects, but existing ML methods often overlook the aleatoric uncertainties inherent in observed data. We introduce Starkindler, a novel training objective that explicitly…

Instrumentation and Methods for Astrophysics · Physics 2025-12-30 Raahul Singh , Ashutosh Pandey

Gravitationally lensed (GL) quasars are brighter than their unlensed counterparts and produce images with distinctive morphological signatures. Past searches and target selection algorithms, in particular the Sloan Quasar Lens Search…

Astrophysics of Galaxies · Physics 2015-06-23 Adriano Agnello , Brandon C. Kelly , Tommaso Treu , Philip J. Marshall

The detection of galaxy clusters in present and future surveys enables measuring mass-to-light ratios, clustering properties or galaxy cluster abundances and therefore, constraining cosmological parameters. We present a new technique for…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-17 Begoña Ascaso , David Wittman , Narciso Benítez , the DLS collaboration

The study of strong-lensing systems conventionally involves constructing a mass distribution that can reproduce the observed multiply-imaging properties. Such mass reconstructions are generically non-unique. Here, we present an alternative…

Astrophysics of Galaxies · Physics 2021-06-30 Philipp Denzel , Sampath Mukherjee , Prasenjit Saha

Photometric redshift estimation is a key requirement for modern large-area surveys, where spectroscopic measurements are observationally prohibitive. Seyfert II galaxies provide a particularly challenging test case due to the combined…

Astrophysics of Galaxies · Physics 2026-04-23 Uzay Aydin

In this work we explore the possibility of applying machine learning methods designed for one-dimensional problems to the task of galaxy image classification. The algorithms used for image classification typically rely on multiple costly…

Astrophysics of Galaxies · Physics 2022-02-23 F. Tarsitano , C. Bruderer , K. Schawinski , W. G. Hartley

In recent decades, large-scale sky surveys such as Sloan Digital Sky Survey (SDSS) have resulted in generation of tremendous amount of data. The classification of this enormous amount of data by astronomers is time consuming. To simplify…

Instrumentation and Methods for Astrophysics · Physics 2022-11-02 Sarvesh Gharat , Yogesh Dandawate

High- to ultrahigh-redshift clustering of halos provides a powerful tool to understand cosmology and galaxy formation. However, theoretical predictions are not firmly established in the first billion years, where current and upcoming…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-17 Kuan Wang , Julian B. Muñoz , L. Y. Aaron Yung

Testing of deep learning models is challenging due to the excessive number and complexity of computations involved. As a result, test data selection is performed manually and in an ad hoc way. This raises the question of how we can…

Machine Learning · Computer Science 2019-05-01 Wei Ma , Mike Papadakis , Anestis Tsakmalis , Maxime Cordy , Yves Le Traon

We apply instance-based machine learning in the form of a k-nearest neighbor algorithm to the task of estimating photometric redshifts for 55,746 objects spectroscopically classified as quasars in the Fifth Data Release of the Sloan Digital…

Currently, machine learning (ML) methods are widely used to process the results of physical experiments. In some cases, due to the limited amount of experimental data, ML-models can be pre-trained on synthetic data simulated based on the…

Computational Physics · Physics 2022-09-22 Y. R. Rodimkov , V. D. Volokitin , I. B. Meyerov , E. S. Efimenko

Magnet errors in storage rings significantly degrade beam performance, impacting the brightness and stability of the light source. Therefore, beam-based correction is crucial for the safe operation of machines and the stability of radiated…

Accelerator Physics · Physics 2025-12-18 Jianhao Xu

One of the most important properties of a galaxy is the total stellar mass, or equivalently the stellar mass-to-light ratio (M/L). It is not directly observable, but can be estimated from stellar population synthesis. Currently, a galaxy's…

Astrophysics of Galaxies · Physics 2019-04-24 Wouter Dobbels , Serge Krier , Stephan Pirson , Sébastien Viaene , Gert De Geyter , Samir Salim , Maarten Baes