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A number of hardware upgrades for the Low-Frequency Array (LOFAR) are currently under development. These upgrades are collectively referred to as the LOFAR 2.0 upgrade. The first stage of LOFAR 2.0 will introduce a distributed clock signal…

Instrumentation and Methods for Astrophysics · Physics 2021-08-11 H. W. Edler , F. de Gasperin , D. Rafferty

Observationally, weak lensing has been served so far by optical surveys due to the much larger number densities of background galaxies achieved, which is typically by two to three orders of magnitude compared to radio. However, the high…

Instrumentation and Methods for Astrophysics · Physics 2016-03-18 Marzia Rivi , Lance Miller , Sphesihle Makhathini , Filipe Batoni Abdalla

We present a search for transient radio sources on time-scales of seconds to hours at 144 MHz using the LOFAR Two-metre Sky Survey (LoTSS). This search is conducted by examining short time-scale images derived from the LoTSS data. To allow…

High Energy Astrophysical Phenomena · Physics 2023-11-15 Iris de Ruiter , Zachary S. Meyers , Antonia Rowlinson , Timothy W. Shimwell , David Ruhe , Ralph A. M. J. Wijers

The morphologies of astronomical sources are highly complex, making it essential not only to classify the identified sources into their predefined categories but also to determine the sources that are most similar to a given query source.…

Image and Video Processing · Electrical Eng. & Systems 2024-10-14 Steven Ndungu , Trienko Grobler , Stefan J. Wijnholds , George Azzopardi

A new sample of radio sources, with the designated name CENSORS (A Combined EIS-NVSS Survey Of Radio Sources), has been defined by combining the NRAO VLA Sky Survey (NVSS) at 1.4 GHz with the ESO Imaging Survey (EIS) Patch D, a 3 by 2…

Astrophysics · Physics 2009-11-10 P. N. Best , J. N. Arts , H. J. A. Rottgering , R. Rengelink , M. H. Brookes , J. Wall

The sensitivity of searches for astrophysical transients in data from the LIGO is generally limited by the presence of transient, non-Gaussian noise artifacts, which occur at a high-enough rate such that accidental coincidence across…

Radio observations of stars trace the plasma conditions and magnetic field properties of stellar magnetospheres and coronae. Depending on the plasma conditions at the emitter site, radio emission in the metre- and decimetre-wave bands is…

Solar and Stellar Astrophysics · Physics 2023-12-13 Timothy W. H. Yiu , Harish K. Vedantham , Joseph R. Callingham , Maximilian N. Günther

The Low Frequency Array (LOFAR) is the only existing radio interferometer able to observe at ultra-low frequencies (<100 MHz) with high resolution (<15") and high sensitivity (<1 mJy/beam). To exploit these capabilities, the LOFAR Surveys…

In this paper we present three different applications, based on deep learning methodologies, that we are developing to support the scientific analysis conducted within the ASKAP-EMU and MeerKAT radio surveys. One employs instance…

Instrumentation and Methods for Astrophysics · Physics 2024-11-14 S. Riggi , T. Cecconello , U. Becciani , F. Vitello

In urban areas, dense buildings frequently block and reflect global positioning system (GPS) signals, resulting in the reception of a few visible satellites with many multipath signals. This is a significant problem that results in…

Machine Learning · Computer Science 2023-06-14 Sanghyun Kim , Jiwon Seo

Extragalactic radio continuum surveys play an increasingly more important role in galaxy evolution and cosmology studies. While radio galaxies and radio quasars dominate at the bright end, star-forming galaxies (SFGs) and radio-quiet Active…

Machine Learning algorithms are good tools for both classification and prediction purposes. These algorithms can further be used for scientific discoveries from the enormous data being collected in our era. We present ways of discovering…

Instrumentation and Methods for Astrophysics · Physics 2021-02-26 Shraddha Surana , Yogesh Wadadekar , Divya Oberoi

For transient sources with timescales of 1-100 seconds, standardized imaging for all observations at each time step become impossible as large modern interferometers produce significantly large data volumes in this observation time frame.…

Instrumentation and Methods for Astrophysics · Physics 2022-04-06 Xia Zhang , Foivos I. Diakogiannis , Richard Dodson , Andreas Wicenec

OCARS (Optical Characteristics of Astrometric Radio Sources) is a compiled catalog of various additional data associated with astrometric radio sources whose coordinates have been determined from very long baseline interferometry (VLBI)…

Instrumentation and Methods for Astrophysics · Physics 2025-05-20 Zinovy Malkin

Red quasi-stellar objects (QSOs) are a subset of the luminous end of the cosmic population of active galactic nuclei (AGN), most of which are reddened by intervening dust along the line-of-sight towards their central engines. In recent work…

Astrophysics of Galaxies · Physics 2020-04-15 D. J. Rosario , V. A. Fawcett , L. Klindt , D. M. Alexander , L. K. Morabito , S. Fotopoulou , E. Lusso , G. Calistro Rivera

To perform precise and accurate photometric catalogue cross-matches -- assigning counterparts between two separate datasets -- we need to describe all possible sources of uncertainty in object position. With ever-increasing time baselines…

Solar and Stellar Astrophysics · Physics 2023-01-23 Tom J. Wilson

The Laser Interferometer Space Antenna (LISA) will observe gravitational waves in a regime that differs sharply from what ground-based detectors such as LIGO handle. Instead of searching for rare signals buried in loud instrumental noise,…

General Physics · Physics 2026-04-20 Jericho Cain

Radio Frequency Interference (RFI) corrupts astronomical measurements, thus affecting the performance of radio telescopes. To address this problem, supervised segmentation models have been proposed as candidate solutions to RFI detection.…

Instrumentation and Methods for Astrophysics · Physics 2022-10-12 Michael Mesarcik , Albert-Jan Boonstra , Elena Ranguelova , Rob V. van Nieuwpoort

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…

In this second paper in a series of papers based on the most-up-to-date catalogue of symbiotic stars (SySts), we present a new approach for identifying and distinguishing SySts from other Halpha emitters in photometric surveys using machine…

Solar and Stellar Astrophysics · Physics 2019-01-16 Stavros Akras , Marcelo L. Leal-Ferreira , Lizette Guzman-Ramirez , Gerardo Ramos-Larios