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We have used the University of Tasmania's 30 m radio telescope at Ceduna in South Australia to regularly monitor the flux density of a number of southern blazars. We report the detection of an annual cycle in the variability timescale of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Steven J. B. Carter , Simon P. Ellingsen , Jean-Pierre Macquart , James E. J. Lovell

Rapid variability in the radio flux density of the BL Lac object PKSB1144-379 has been observed at four frequencies, ranging from 1.5 to 15 GHz, with the VLA and the University of Tasmania's Ceduna antenna. Intrinsic and line of sight…

High Energy Astrophysical Phenomena · Physics 2015-06-05 R. J. Turner , S. P. Ellingsen , S. S. Shabala , J. Blanchard , J. E. J. Lovell , J. N. McCallum , G. Cimo

We discovered rapid intra-day variability in radio source PMN J1726+0639 at GHz frequencies, during a survey to search for such variability with the Australia Telescope Compact Array. Follow-up observations were conducted over two years and…

Astrophysics of Galaxies · Physics 2022-04-27 Hayley E. Bignall , Artem V. Tuntsov , Jamie Stevens , Keith Bannister , Mark A. Walker , Cormac Reynolds

Rapid radio intra-day variability (IDV) has been discovered in the southern quasar PKS 1257-326. Flux density changes of up to 40% in as little as 45 minutes have been observed in this source, making it, along with PKS 0405-385 and…

The search for long-term variability of compact components of radio sources B0821+394 and B1812+412 over an interval of 10 years was carried out. The LPA LPI radio telescope with an operating frequency of 111 MHz was used for observations.…

High Energy Astrophysical Phenomena · Physics 2025-04-16 S. A. Tyul'bashev , I. V. Chashei , I. A. Grishanova , G. E. Tyul'basheva , I. A. Subaev

Interstellar scintillation has been conclusively demonstrated to be the principal cause of the intraday variability (IDV) observed in the centimetre-wavelength emission of many AGN. A few sources show large amplitude modulation in their…

PKS B1322-110 is a radio quasar that is located only 8.5' in angular separation from the bright B star Spica. It exhibits intra-day variability in its flux density at GHz frequencies attributed to scintillations from plasma inhomogeneities.…

Annual variations of interstellar scintillation can be modelled to constrain parameters of the ionized interstellar medium. If a pulsar is in a binary system, then investigating the orbital parameters is possible through analysis of the…

We report measurements of time delays of up to 8 minutes in the centimeter wavelength variability patterns of the intra-hour scintillating quasar PKS 1257-326 as observed between the VLA and the ATCA on three separate epochs. These time…

We have observed the relativistic binary pulsar PSR J1141$-$6545 over a period of $\sim$6 years using the Parkes 64 m radio telescope, with a focus on modelling the diffractive intensity scintillations to improve the accuracy of the…

High Energy Astrophysical Phenomena · Physics 2019-03-20 D. J. Reardon , W. A. Coles , G. Hobbs , S. Ord , M. Kerr , M. Bailes , N. D. R. Bhat , V. Venkatraman Krishnan

The interstellar scintillation observed in radio pulsars arises from interference between electromagnetic waves scattered by electron density fluctuations in the turbulent interstellar plasma, providing a critical tool for probing the…

We model long-term variations in the scintillation of binary pulsar PSR J1603$-$7202, observed by the 64 m Parkes radio telescope (Murriyang) between 2004 and 2016. We find that the time variation in the scintillation arc curvature is…

High Energy Astrophysical Phenomena · Physics 2022-07-06 Kris Walker , Daniel J. Reardon , Eric Thrane , Rory Smith

Analysis of rapid variability at 4.85 GHz for the BL BLac object 0925+504 is presented and discussed. The structure functions (SF) are investigated with both refractive and weak interstellar scintillation (RISS/WISS) models analytically.…

Astrophysics of Galaxies · Physics 2018-04-26 Jun Liu , Xiang Liu

Compact radio sources exhibit scintillation, an interference pattern arising from propagation through inhomogeneous plasma, where scintillation patterns encode the relative distances and velocities of the source, scattering material, and…

High Energy Astrophysical Phenomena · Physics 2023-06-26 R. A. Main , S. Bethapudi , V. R. Marthi , M. L. Bause , D. Z. Li , H. -H. Lin , L. G. Spitler , R. S. Wharton

We have conducted the first systematic search for interday variability in a large sample of extragalactic radio sources at 15 GHz. From the sample of 1158 radio-selected blazars monitored over a $\sim$10 year span by the Owens Valley Radio…

Comparing the asymmetry coefficients and scintillation indices for observed time variations of the intensity of the radiation of extragalactic sources and the predictions of theoretical models is a good test of the nature of the observed…

Astrophysics · Physics 2009-11-11 V. I. Shishov , T. V. Smirnova , S. A. Tyul'bashev

Observations over the last two decades have shown that a significant fraction of all flat-spectrum, extragalactic radio sources exhibit flux density variations on timescales of a day or less at frequencies of several GHz. It has been…

We present an analysis of interplanetary scintillation (IPS) observations conducted with the Arecibo 305-m radio telescope during the minimum phase at the end of solar cycle 24 and the onset of solar cycle 25. These observations span a…

Solar and Stellar Astrophysics · Physics 2025-02-25 P. K. Manoharan , C. J. Salter

We present the results of flux density monitoring of PSR B0329+54 at the frequency of 4.8 GHz using the 32-meter TCfA radiotelescope. The observations were conducted between 2002 and 2005. The main goal of the project was to find…

Astrophysics of Galaxies · Physics 2015-05-28 Wojciech Lewandowski , Jaroslaw Kijak , Yashwant Gupta , Krzysztof Krzeszowski

The remarkable rapid variations in radio flux density and polarization of the quasar PKS 0405-385 observed in 1996 are subject to a correlation analysis, from which characteristic time scales and amplitudes are derived. The variations are…

Astrophysics · Physics 2009-11-07 Barney J. Rickett , Lucyna Kedziora-Chudczer , David L. Jauncey
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