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In this work, we explore methods to improve galaxy redshift predictions by combining different ground truths. Traditional machine learning models rely on training sets with known spectroscopic redshifts, which are precise but only represent…

Instrumentation and Methods for Astrophysics · Physics 2024-11-28 Jonathan Soriano , Srinath Saikrishnan , Vikram Seenivasan , Bernie Boscoe , Jack Singal , Tuan Do

This paper presents a comprehensive study of quasar photometric classification and redshift estimation using machine learning techniques. We cross-matched photometric data from the Dark Energy Survey Data Release 2 (DES DR2) with…

Instrumentation and Methods for Astrophysics · Physics 2026-05-19 Pablo Motta , Filipe B. Abdalla , Elcio Abdalla , Gabriel S. Costa , Camila Cardoso

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…

Aims. We present the application of a fully connected neural network (NN) for galaxy merger identification using exclusively photometric information. Our purpose is not only to test the method's efficiency, but also to understand what…

Astrophysics of Galaxies · Physics 2023-01-25 L. E. Suelves , W. J. Pearson , A. Pollo

With the aim of using machine learning techniques to obtain photometric redshifts based upon a source's radio spectrum alone, we have extracted the radio sources from the Million Quasars Catalogue. Of these, 44,119 have a spectroscopic…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-25 S. J. Curran , J. P. Moss , Y. C. Perrott

The Early Data Release from the Sloan Digital Sky survey provides one of the largest multicolor photometric catalogs currently available to the astronomical community. In this paper we present the first application of photometric redshifts…

In order to understand the formation and subsequent evolution of galaxies one must first distinguish between the two main morphological classes of massive systems: spirals and early-type systems. This paper introduces a project, Galaxy Zoo,…

We analyze MegaZ-LRG, a photometric-redshift catalogue of Luminous Red Galaxies (LRGs) based on the imaging data of the Sloan Digital Sky Survey (SDSS) 4th Data Release. MegaZ-LRG, presented in a companion paper, contains 10^6 photometric…

Astrophysics · Physics 2009-05-29 Chris Blake , Adrian Collister , Sarah Bridle , Ofer Lahav

We created a catalog of photometric redshift of ~3,000,000 SDSS galaxies annotated by their broad morphology. The photometric redshift was optimized by testing and comparing several pattern recognition algorithms and variable selection…

Astrophysics of Galaxies · Physics 2018-06-12 Nicholas Paul , Nicholas Virag , Lior Shamir

We propose a Multimodal Machine Learning method for estimating the Photometric Redshifts of quasars (PhotoRedshift-MML for short), which has long been the subject of many investigations. Our method includes two main models, i.e. the feature…

Astrophysics of Galaxies · Physics 2022-11-09 Shuxin Hong , Zhiqiang Zou , A-Li Luo , Xiao Kong , Wenyu Yang , Yanli Chen

We present a morphological catalogue for $\sim$ 670,000 galaxies in the Sloan Digital Sky Survey in two flavours: T-Type, related to the Hubble sequence, and Galaxy Zoo 2 (GZ2 hereafter) classification scheme. By combining accurate existing…

Astrophysics of Galaxies · Physics 2018-02-28 H. Domínguez Sánchez , M. Huertas-Company , M. Bernardi , D. Tuccillo , J. L. Fischer

We want to derive bias free, accurate photometric redshifts for those fields of the CFHTLS-Wide data which are covered in the u*, g', r', i' and z' filters and are public on January 2008. These are 37 square degrees in the W1, W3 and W4…

Astrophysics · Physics 2008-11-21 Fabrice Brimioulle , Michael Lerchster , Stella Seitz , Ralf Bender , Jan Snigula

Correlating BASS DR3 catalogue with ALLWISE database, the data from optical and infrared information are obtained. The quasars from SDSS are taken as training and test samples while those from LAMOST are considered as external test sample.…

Instrumentation and Methods for Astrophysics · Physics 2021-11-17 Changhua Li , Yanxia Zhang , Chenzhou Cui , Dongwei Fan , Yongheng Zhao , Xue-Bing Wu , Jing-Yi Zhang , Jun Han , Yunfei Xu , Yihan Tao , Shanshan Li , Boliang He

We present SHEEP, a new machine learning approach to the classic problem of astronomical source classification, which combines the outputs from the XGBoost, LightGBM, and CatBoost learning algorithms to create stronger classifiers. A novel…

Instrumentation and Methods for Astrophysics · Physics 2022-10-19 P. A. C. Cunha , A. Humphrey

Measuring the morphological parameters of galaxies is a key requirement for studying their formation and evolution. Surveys such as the Sloan Digital Sky Survey (SDSS) have resulted in the availability of very large collections of images,…

Instrumentation and Methods for Astrophysics · Physics 2015-03-25 Sander Dieleman , Kyle W. Willett , Joni Dambre

We apply machine learning in the form of a nearest neighbor instance-based algorithm (NN) to generate full photometric redshift probability density functions (PDFs) for objects in the Fifth Data Release of the Sloan Digital Sky Survey (SDSS…

In this work I discuss the necessary steps for deriving photometric redshifts for luminous red galaxies (LRGs) and galaxy clusters through simple empirical methods. The data used is from the Sloan Digital Sky Survey (SDSS). I show that with…

Astrophysics · Physics 2009-02-10 P. A. A. Lopes

Accurate photometric redshifts are a lynchpin for many future experiments to pin down the cosmological model and for studies of galaxy evolution. In this study, a novel sparse regression framework for photometric redshift estimation is…

Instrumentation and Methods for Astrophysics · Physics 2025-06-03 Ibrahim A. Almosallam , Sam N. Lindsay , Matt J. Jarvis , Stephen J. Roberts

We present optical and near-infrared imaging covering a $\sim$1.53 deg$^2$ region in the Super-Cluster Assisted Shear Survey (SuperCLASS) field, which aims to make the first robust weak lensing measurement at radio wavelengths. We derive…