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We present here the discovery of rapid, large amplitude intraday variability in the compact flat-spectrum radio quasar 1156+295. The detection of 40% flux density variations at 15 GHz on a timescale of only 2.7 hours was serendipitously…

Astrophysics · Physics 2009-04-14 T. Savolainen , Y. Y. Kovalev

To increase the number of sources with Very Long Baseline Interferometry (VLBI) astrometry available for comparison with the Gaia results, we have observed 31 young stars with recently reported radio emission. These stars are all in the…

Solar and Stellar Astrophysics · Physics 2024-06-12 Sergio A. Dzib , Laurent Loinard , Ralf Launhardt , Jazmín Ordóñez-Toro

Aims: The knowledge of the properties of the youngest radio sources is very important in order to trace the earliest phase of the evolution of the radio emission. RXJ1459+3337, with its high turnover frequency (~25 GHz) provides a unique…

Astrophysics · Physics 2009-11-13 M. Orienti , D. Dallacasa

We present the observational results from the 43-GHz Very Long Baseline Array (VLBA) observations of 124 compact radio-loud active galactic nuclei (AGNs) that were conducted between 2014 November and 2016 May. The typical dimensions of the…

High Energy Astrophysical Phenomena · Physics 2020-07-07 X. -P. Cheng , T. An , S. Frey , X. -Y. Hong , X. He , K. I. Kellermann , M. L. Lister , B. -Q. Lao , X. -F. Li , P. Mohan , J. Yang , X. -C. Wu , Z. -L. Zhang , Y. -K. Zhang , W. Zhao

We address the question of why low-luminosity radio sources with similar flat radio spectra show a range of optical activity. The investigation is based on the spectral energy distributions (SEDs) of objects from the 200 mJy sample. We…

Astrophysics · Physics 2015-06-11 S. Anton , I. W. A. Browne , M. J. M. Marcha , M. Bondi , A. Polatidis

We search for variable sources, using the data of the surveys conducted on the RATAN-600 radio telescope in 1980-1994 at 3.94 GHz. To test the radio sources of the RCR (RATAN Cold Refined) catalog for variability, we estimated the long-term…

Astrophysics of Galaxies · Physics 2014-09-15 E. K. Majorova , O. P. Zelenkova

We present simultaneous multifrequency radio observations for a complete subsample of 26 XBLs from the Einstein Extended Medium-Sensitivity Survey, obtained with the Very Large Array (VLA). Spectra are computed using fluxes at 20, 6 and 3.6…

Astrophysics · Physics 2009-11-10 Francesca Cavallotti , Anna Wolter , John T. Stocke , Travis Rector

We present high-angular-resolution ($\sim0\rlap{.}''1$) VLA Ku-band (12--18 GHz) observations of two explosive molecular outflows (EMOs), DR 21 and G5.89, in a search for runaway stars related to these explosive events. In DR 21, we…

Solar and Stellar Astrophysics · Physics 2025-12-22 Vanessa Yanza , Sergio A. Dzib , Aina Palau , William J. Henney , Luis F. Rodríguez , Luis A. Zapata

Wide-field surveys are a commonly-used method for studying thousands of objects simultaneously, to investigate, e.g., the joint evolution of star-forming galaxies and active galactic nuclei. VLBI observations can yield valuable input to…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Enno Middelberg , Adam Deller , John Morgan , Helge Rottmann , Walter Alef , Steven Tingay , Ray Norris , Uwe Bach , Walter Brisken , Emil Lenc

We present the data and analysis of VLBI observations at 1.6, 5 and 15 GHz of a sample of faint Gigahertz Peaked Spectrum (GPS) sources selected from the Westerbork Northern Sky Survey (WENSS). The 5 GHz observations involved a global array…

Astrophysics · Physics 2016-08-30 Ignas Snellen , Richard Schilizzi , Huib-Jan van Langevelde

We analyze results of data processing of observations of well-known object titled SS433 with the VLBA during more than 10 years. Data have been processed with the software project titled 'Astro Space Locator' (ASL for Windows). The Multi…

Astrophysics of Galaxies · Physics 2016-09-08 A. A. Chuprikov , I. A. Guirin

Based on the FIRST and SDSS catalogues a flux density limited sample of weak Compact Steep Spectrum (CSS) sources with radio luminosity below 10^26 [W/Hz] at 1.4 GHz has been constructed. Our previous multifrequency observations of CSS…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-11 Magdalena Kunert-Bajraszewska , Peter Thomasson

We aim to confirm the compact nature and constrain the radio spectra of candidate persistent radio sources (PRSs) associated with repeating fast radio bursts (FRBs). We performed European VLBI Network (EVN) observations at 5 and 8 GHz…

High Energy Astrophysical Phenomena · Physics 2026-04-07 G. Bruni , L. Piro , Y. -P. Yang , L. Nicastro , A. Rossi , E. Palazzi , E. Maiorano , S. Savaglio , B. Zhang

We present the results of a survey of radio continuum sources near the Galactic plane using the Very Long Baseline Array (VLBA). Our observations are designed to identify compact extragalactic sources of milliarcsecond size that can be used…

Astrophysics of Galaxies · Physics 2015-05-27 K. Immer , A. Brunthaler , M. J. Reid , A. Bartkiewicz , Y. K. Choi , K. M. Menten , L. Moscadelli , A. Sanna , Y. W. Wu , Y. Xu , B. Zhang , X. W. Zheng

Young stellar objects are known to exhibit strong radio variability on timescales of weeks to months, and a few reports have documented extreme radio flares, with at least an order of magnitude change in flux density on timescales of hours…

High Energy Astrophysical Phenomena · Physics 2017-08-02 Jan Forbrich , Mark J. Reid , Karl M. Menten , Victor Rivilla , Scott J. Wolk , Urvashi Rau , Claire J. Chandler

We present high-resolution observations made with the Very Large Array (VLA) in its A configuration at frequencies between 5 and 43 GHz of a sample of five massive young stellar objects (YSOs): LkHa101, NGC2024-IRS2, S106-IR, W75N and…

Astrophysics · Physics 2009-11-13 A. G. Gibb , M. G. Hoare

We present the description and early results of the mJy Imaging VLBA Exploration at 20 cm (mJIVE-20). mJIVE-20 is a large project on the Very Long Baseline Array which uses "filler" time to systematically inspect a large sample of mJy radio…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 A. T. Deller , E. Middelberg

We present a catalog of 246 radio sources found in the central 1 degree of the COSMOS field at 1.4GHz. The VLA pilot project data have a resolution of 1.9"x1.6" and an rms noise limit of ~25-100uJy/beam covering 0.837 sqrdeg. About 20 radio…

We have conducted VLBA 1.4 GHz (L-band) continuum observations towards twelve sources with HI 21-cm absorption detections at redshift $0.4<z<0.7$ in the pilot surveys of FLASH, an ongoing survey with the ASKAP radio telescope. 11 of the 12…

We present high angular resolution imaging of the quasar PSO J172.3556+18.7734 at $z=6.82$ with the Very Long Baseline Array (VLBA). This source currently holds the record of being the highest redshift radio-loud quasar. These observations…

Astrophysics of Galaxies · Physics 2021-04-14 Emmanuel Momjian , Eduardo Bañados , Christopher L. Carilli , Fabian Walter , Chiara Mazzucchelli
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