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We present the results of comparative study of amplitude calibrations for East-Asia VLBI Network (EAVN) at 22 and 43 GHz using two different methods of an "a-priori" and a "template spectrum", particularly on lower declination sources.…

To locate and image the compact emission regions in quasars, which are closely connected to the phenomenon of IntraDay Variability (IDV), space VLBI observations are of prime importance. Here we report on VSOP observations of two prominent…

Extension of very long baseline interferometry (VLBI) to observing wavelengths shorter than 1.3mm provides exceptional angular resolution (~20 micro arcsec) and access to new spectral regimes for the study of astrophysical phenomena. To…

Instrumentation and Methods for Astrophysics · Physics 2011-06-02 Sheperd Doeleman , Tao Mai , Alan Rogers , John Hartnett , Michael Tobar , Nitin Nand

We present the results of a second epoch of 18cm global Very Long-Baseline Interferometry (VLBI) observations, taken on 23 February 2001, of the central kiloparsec of the nearby starburst galaxy Messier 82. These observations further…

We present astrometric results on two millisecond pulsars, PSR B1257+12 and PSR J1022+1001, as carried out through VLBI. For PSR B1257+12, a model-independent distance of $710_{\rm -38}^{\rm +43}$ pc and proper motion of ($\mu_{\rm…

Solar and Stellar Astrophysics · Physics 2015-06-12 Zhen Yan , Zhi-qiang Shen , Jian-ping Yuan , Na Wang , Helge Rottmann , Walter Alef

We report on a very long baseline interferometry (VLBI) experiment on giant radio pulses (GPs) from the Crab pulsar in the radio 1.4 to 1.7 GHz range to demonstrate a VLBI technique for searching for fast radio bursts (FRBs). We carried out…

Instrumentation and Methods for Astrophysics · Physics 2016-06-29 K. Takefuji , T. Terasawa , T. Kondo , R. Mikami , H. Takeuchi , H. Misawa , F. Tsuchiya , H. Kita , M. Sekido

We present the results of EVN polarization observations of fourteen GHz-Peaked-Spectrum (GPS) radio sources at 5 GHz. These sources were selected from bright GPS source samples and we aimed at finding Compact Symmetric Objects (CSOs). We…

Astrophysics · Physics 2016-08-30 Liu Xiang , Cormac Reynolds , Richard Strom , Daniele Dallacasa

We present results from a large global VLBI(Very Long Baseline Interferometry) survey of compact radio sources at 86 GHz which started in October 2001. The main goal of the survey is to increase the total number of objects accessible for…

Astrophysics · Physics 2009-04-14 S. Lee , A. P. Lobanov , T. P. Krichbaum , A. Witzel , J. A. Zensus , M. Bremer , A. Greve , M. Grewing

PSR J0218$+$4232 is a millisecond pulsar (MSP) with a flux density $\sim$ 0.9 mJy at 1.4 GHz. It is very bright in the high-energy X-ray and $\gamma$-ray domains. We conducted an astrometric program using the European VLBI Network (EVN) at…

Solar and Stellar Astrophysics · Physics 2014-02-12 Yuanjie Du , Jun Yang , Robert M. Campbell , Gemma Janssen , Ben Stappers , Ding Chen

We performed two types of radiation testing on high-speed LSI chips to test their suitability for use in wideband observations by the Japanese next space VLBI mission, VSOP-2. In the total ionization dose experiment we monitored…

Astrophysics · Physics 2015-05-13 Kiyoaki Wajima , Noriyuki Kawaguchi , Yasuhiro Murata , Hisashi Hirabayashi

We present multi-frequency VLBI observations of the Compact Steep-spectrum Quasar 3C147 (0538+498) made with the VLBA at the four frequencies in the available 5 GHz band and at 8.4 GHz (still under analysis), from which we derived…

Astrophysics · Physics 2007-05-23 A. Rossetti , F. Mantovani , D. Dallacasa

The Shanghai Astronomical Observatory (SHAO) of the Chinese Academy of Sciences (CAS) is studying a space VLBI (Very Long Baseline Interferometer) program. The ultimate objective of the program is to image the immediate vicinity of the…

Instrumentation and Methods for Astrophysics · Physics 2014-07-01 Xiaoyu Hong , Zhiqiang Shen , Tao An , Qinghui Liu , the Chinese Space VLBI Array team

The DISTO collaboration has built a large-acceptance magnetic spectrometer designed to provide broad kinematic coverage of multi-particle final states produced in $pp$ scattering. The spectrometer has been installed in the polarized proton…

High Energy Physics - Experiment · Physics 2012-08-27 The DISTO Collaboration

Advancements in VLBI instrumentation, driven by the geodetic community's goal of achieving positioning accuracy of 1 mm and stability of 0.1 mm/y, have led to the development of new broadband systems. Here, we assess the potential of these…

Solar and Stellar Astrophysics · Physics 2025-04-23 A. Jaradat , G. Molera Calvés , J. Edwards , S. Ellingsen , T. McCarthy , J. Morgan

The Gaia celestial reference frame (Gaia-CRF) will benefit from a close assessment with independent methods, such as Very Long Baseline Interferometry (VLBI) measurements of radio stars at bright magnitudes. However, obtaining full…

Instrumentation and Methods for Astrophysics · Physics 2024-03-27 Jingdong Zhang , Bo Zhang , Shuangjing Xu , Niu Liu , Wen Chen , Hao Ding , Pengfei Jiang , Yan Sun , Jinqing Wang , Lang Cui , Shiming Wen , Xiaofeng Mai , Jinling Li , Fengchun Shu , Yidan Huang

A review is given on the current status and selected results from large VLBI surveys of compact extragalactic radio sources made between 13 cm and 3 mm wavelengths and covering the entire sky. More than 4200 objects are observed and imaged…

Astrophysics · Physics 2009-07-22 Y. Y. Kovalev

Demands for implementing original OSs that can achieve high I/O performance on PC/AT compatible hardware have recently been increasing, but conventional OS debugging environments have not been able to simultaneously assure their stability,…

Operating Systems · Computer Science 2011-11-09 Tadashi Takeuchi

The Ghana Radio Astronomy Observatory (GRAO) marks a pivotal advance in African radio astronomy through the successful transformation of a decommissioned 32 m satellite communication antenna into a scientifically capable, VLBI-ready radio…

Precision astrometry is an integral component of successful pulsar timing campaigns. Astrometric parameters are commonly derived by fitting them as parameters of a timing model to a series of pulse times of arrival (TOAs). TOAs measured to…

High Energy Astrophysical Phenomena · Physics 2013-12-12 D. R. Madison , S. Chatterjee , J. M. Cordes

To determine the location of the intra-day variable (IDV) emission region within the jet of the BL Lac object S5 0716+714, a multi-epoch VSOP polarization experiment was performed in Autumn 2000. To detect, image, and monitor the short term…

Astrophysics · Physics 2009-11-11 U. Bach , T. P. Krichbaum , A. Kraus , A. Witzel , J. A. Zensus