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Compact radio cores in radio-loud active galactic nuclei (AGNs) are classical targets of Very-Long-Baseline interferometric (VLBI) research. Until today little has been known about their X-ray properties in comparison to radio-quiet AGNs.…

天体物理学 · 物理学 2007-05-23 M. Kadler , E. Ros , J. Kerp , Y. Y. Kovalev , J. A. Zensus

New observations of Sgr A have been carried out with the VLA using the broadband (2 GHz) continuum mode at 5.5 GHz, covering the central 30 pc region of the RBZ at the Galactic center. Using the MS-MFS algorithms in CASA, we have imaged Sgr…

星系天体物理 · 物理学 2016-02-17 Jun-Hui Zhao , Mark R. Morris , W. M. Goss

Cosmology with large interferometric telescopes is a rich and largely unexplored subject, involving three types of measurement: astrometric measurement of absolute distances and proper motions, dispersions of relative proper motions, and…

天体物理学 · 物理学 2007-05-23 David Tytler

We present a novel approach to model the nearby stars Alpha Cen A & B and Procyon A using asteroseismic and interferometric constraints. Using the VINCI instrument installed at the VLT Interferometer (VLTI), the angular diameters of the…

天体物理学 · 物理学 2007-05-23 P. Kervella , F. Thevenin , P. Morel , G. Berthomieu , J. Provost , P. Borde , D. Segransan

This thesis focuses on dealing with the task of acoustic scene classification (ASC), and then applied the techniques developed for ASC to a real-life application of detecting respiratory disease. To deal with ASC challenges, this thesis…

声音 · 计算机科学 2021-07-21 Lam Pham

Fast radio bursts (FRBs) constitute an emerging class of fast radio transient whose origin continues to be a mystery. Realizing the importance of increasing coverage of the search parameter space, we have designed, built, and deployed a…

The VLTI Spectro Imager project aims to perform imaging with a temporal resolution of 1 night and with a maximum angular resolution of 1 milliarcsecond, making best use of the Very Large Telescope Interferometer capabilities. To fulfill the…

High precision astrometric Space Very Long Baseline Interferometry (S-VLBI) at the low end of the conventional frequency range, i.e. 20cm, is a requirement for a number of high priority science goals. These are headlined by obtaining…

天体物理仪器与方法 · 物理学 2015-06-15 R. Dodson , M. Rioja , Y. Asaki , H. Imai , X. -Y. Hong , Z. Shen

Over the past few decades, researchers have developed several approaches such as the Reference Phantom Method (RPM) to estimate ultrasound attenuation coefficient (AC) and backscatter coefficient (BSC). AC and BSC can help to discriminate…

医学物理 · 物理学 2017-12-12 Kajoli Banerjee Krishnan , Nithin Nagaraj , Nitin Singhal , Shalini Thapar , Komal Yadav

The space astrometry mission GAIA will construct a dense optical QSO-based celestial reference frame. For consistency between the optical and radio positions, it will be important to align the GAIA frame and the International Celestial…

天体物理学 · 物理学 2009-11-13 Geraldine Bourda , Patrick Charlot , Richard Porcas , Simon Garrington

We present result of processing of data of ground-space VLBI experiment titled W068. Particularly, one part of data of that observational session is successfully processed. These data were obtained on 2000 March 17 between 9:00 UT and 10:30…

宇宙学与河外天体物理 · 物理学 2015-05-27 Andrey Chuprikov , Igor Guirin

The alignment between the radio-based International Celestial Reference Frame (ICRF) and the optical Gaia Celestial Reference Frame (Gaia-CRF) is critical for multi-waveband astronomy, yet systematic offsets at the optical bright end (G<13)…

A space-based very long baseline interferometry (VLBI) programme, named as the Cosmic Microscope, is proposed to involve dual VLBI telescopes in the space working together with giant ground-based telescopes (e.g., Square Kilometre Array,…

天体物理仪器与方法 · 物理学 2022-05-19 Tao An , Sumit Jaiswal , Prashanth Mohan , Zhen Zhao , Baoqiang Lao

To accurately link the radio and optical Celestial Reference Frames (CRFs) at optical bright end, i.e., with Gaia G band magnitude < 13, increasing number and improving sky distribution of radio stars with accurate astrometric parameters…

太阳与恒星天体物理 · 物理学 2023-05-03 Wen Chen , Bo Zhang , Jingdong Zhang , Jun Yang , Shuangjing Xu , Yan Sun , Xiaofeng Mai , Fengchun Shu , Min Wang

We report results from the first Earth-space VLBI observations of the Galactic Center supermassive black hole, Sgr A*. These observations used the space telescope Spektr-R of the RadioAstron project together with a global network of 20…

Ground-space interferometer RadioAstron provides unique opportunity to probe detail structure of the distant active galactic nuclei at $\mu$as scales. Here we report on RadioAstron observations of the BL Lac object S5 0716$+$71, performed…

星系天体物理 · 物理学 2020-01-09 E. V. Kravchenko , J. L. Gómez , Y. Y. Kovalev , P. A. Voytsik

We present an all-sky catalog of absolute positions and estimates of correlated flux density of 21,942 compact radio sources determined from processing interferometric visibility data of virtually all very long baseline interferometry…

天体物理仪器与方法 · 物理学 2025-01-20 Leonid Petrov , Yuri Y. Kovalev

We introduce the cross spectrum based FRB (Fast Radio Burst) search method for VLBI observation. This method optimizes the fringe fitting scheme in geodetic VLBI data post processing, which fully utilizes the cross spectrum fringe phase…

天体物理仪器与方法 · 物理学 2018-02-06 Lei Liu , Fengxian Tong , Weimin Zheng , Juan Zhang , Li Tong

The space astrometry mission GAIA will construct a dense optical QSO-based celestial reference frame. For consistency between the optical and radio positions, it will be important to align the GAIA frame and the International Celestial…

天体物理学 · 物理学 2008-12-18 G. Bourda , P. Charlot , R. Porcas , S. Garrington

Radio astronomy is uniquely coupled to exponential trends in computation because the optics (cross-correlation, beamforming, and imaging) and spectrometry (i.e. channelization) can now be done digitally. Inexpensive analog-to-digital…