Results 81 to 90 of about 11,697 (215)

Cross‐Polarization Gain Calibration of Linearly Polarized VLBI Antennas by Observations of 4C 39.25

Radio Science, Volume 59, Issue 4, April 2024.
Abstract Radio telescopes with dual linearly polarized feeds regularly participate in Very Long Baseline Interferometry. One example is the VLBI Global Observing System (VGOS), which is employed for high‐precision geodesy and astrometry. In order to achieve the maximum signal‐to‐noise ratio, the visibilities of all four polarization products are ...
F. Jaron, I. Martí‐Vidal, M. Schartner, J. González‐García, E. Albentosa‐Ruiz, S. Bernhart, J. Böhm, J. Gruber, S. Modiri, A. Nothnagel, V. Pérez‐Díez, T. Savolainen, B. Soja, E. Varenius, M. H. Xu   +14 more
wiley   +1 more source

Prototype System for Unmanned Reference Point Determination at the Sub‐Millimeter Level

Earth and Space Science, Volume 11, Issue 2, February 2024.
Abstract The determination of reference points for telescopes is crucial for obtaining the local‐tie vector for a multi‐technology co‐located station. Traditional methods suffer from labor‐intensive fieldwork, long execution cycles, and systematic errors due to the incident angle of the total station's laser beam on the prism. In this paper, we propose
Zhibin Zhang, Zhikang Wang, Xiaohui Ma, Zhengxiong Sun, Dezhen Xu, Chengli Huang, Guangli Wang, Zhaoxiang Qi   +7 more
wiley   +1 more source

Infrared-radio-follow-up observations for detection of the magnetic radio emission of extra solar planets: a new window to detect exoplanets

Frontiers in Astronomy and Space Sciences
There are several methods for indirectly detecting exoplanets, such as transit, radial velocity, astrometry, and the conventional gravitational microlensing approach.
Fatemeh Bagheri, Fatemeh Bagheri, Ramon E. Lopez, Amir Shahmoradi, Amir Shahmoradi   +4 more
doaj   +1 more source

Imaging Simulations for the Korean VLBI Network (KVN) [PDF]

Journal of Astronomy and Space Sciences, 2005
The Korean VLBI Network (KVN) will open a new field of research in astronomy, geodesy and earth science using the newest three 21m radio telescopes. This will expand our ability to look at the Universe in the millimeter regime.
Tae-Hyun Jung, Myung-Hyun Rhee, Duk-Gyoo Roh, Hyun-Goo Kim, Bong-Won Sohn   +4 more
doaj   +1 more source

Milliarcsecond-Accurate Astrometry of 34 Southern Hemisphere Radio Sources [PDF]

The Astronomical Journal, 2006
Milliarcsecond-accurate radio positions in the International Celestial Reference Frame for 34 southern hemisphere extragalactic sources are reported. The positions are derived from Mark III/IV very long baseline interferometry observations made between 2004 August and 2006 April using radio telescopes located in Australia, South Africa, and Hawaii ...
Alan L. Fey, Roopesh Ojha, Jonathan F. H. Quick, George D. Nicolson, James E. J. Lovell, John E. Reynolds, Simon P. Ellingsen, Peter M. McCulloch, Kenneth J. Johnston, David L. Jauncey, Anastasios K. Tzioumis   +10 more
openaire   +1 more source

The Global Shape, Gravity Field, and Libration of Enceladus

Journal of Geophysical Research: Planets, Volume 129, Issue 1, January 2024.
Abstract In order to improve our understanding of the interior structure of Saturn's small moon Enceladus, we reanalyze radiometric tracking and onboard imaging data acquired by the Cassini spacecraft during close encounters with the moon. We compute the global shape, gravity field, and rotational parameters of Enceladus in a reference frame consistent
R. S. Park, N. Mastrodemos, R. A. Jacobson, A. Berne, A. T. Vaughan, D. J. Hemingway, E. J. Leonard, J. C. Castillo‐Rogez, C. S. Cockell, J. T. Keane, A. S. Konopliv, F. Nimmo, J. E. Riedel, M. Simons, S. Vance   +14 more
wiley   +1 more source

Varstrometry for Off-nucleus and Dual Sub-kiloparsec Active Galactic Nuclei (VODKA): Very Long Baseline Array Searches for Dual or Off-nucleus Quasars and Small-scale Jets

The Astrophysical Journal, 2023
Dual and off-nucleus active supermassive black holes are expected to be common in the hierarchical structure formation paradigm, but their identification at parsec scales remains a challenge due to strict angular resolution requirements.
Yu-Ching Chen, Xin Liu, Joseph Lazio, Peter Breiding, Sarah Burke-Spolaor, Hsiang-Chih Hwang, Yue Shen, Nadia L. Zakamska   +7 more
doaj   +1 more source

The catalogue of positions of optically bright extragalactic radio sources OBRS-1

, 2011
It is expected that the European Space Agency mission Gaia will make possible to determine coordinates in the optical domain of more than 500000 quasars.
Beasley, Charlot, Condon, Fomalont, Helmboldt, Kovalev, L. Petrov, Lanyi, Lindegren, Ma, Matveenko, Mignard, Petrov, Petrov, Petrov, Petrov, Petrov, Piner, Pushkarev, Taylor, Zacharias   +20 more
core   +1 more source

Optical Astrometry of Extragalactic Radio Sources With the Tautenburg Schmidt Telescope [PDF]

Symposium - International Astronomical Union, 1990
Optical positions of objects from the IAU Commission 24 Working Group list of benchmark radio sources have been derived which will contribute to the link of the radio and optical reference frames. Results for 11 objects with an r.m.s. position error of 0.″2 are presented and discussed.
W. R. Dick, I. I. Kumkova
openaire   +1 more source

Serial MultiView: An Efficient Approach to Mitigating Atmospheric Spatial-structure Errors for Very-long-baseline-interferometry Astrometry

The Astronomical Journal
Atmospheric propagation errors are a main constraint on the accuracy of very-long-baseline-interferometry astrometry. For relative astrometry, differential techniques can mitigate these errors, but their effectiveness diminishes with decreasing elevation
Jingdong Zhang, Bo Zhang, Shuangjing Xu, Maria J. Rioja, Richard Dodson, Xiaofeng Mai, Oleg Titov   +6 more
doaj   +1 more source