Zobrazeno 1 - 10
of 15
pro vyhledávání: '"Aletha De Witt"'
Publikováno v:
The Astronomical Journal, Vol 165, Iss 2, p 49 (2023)
Sagittarius A* (Sgr A*) is a strong, compact radio source believed to be powered by a supermassive black hole at the galactic center. Extinction by dust and gas in the galactic plane prevents observing it optically, but its position and proper motion
Externí odkaz:
https://doaj.org/article/c0f5bbbe64fa4b5dae644522deffc80c
Autor:
Oleg Titov, Sándor Frey, Alexey Melnikov, Fengchun Shu, Bo Xia, Javier González, Belén Tercero, Leonid Gurvits, Aletha de Witt, Jamie McCallum, Mikhail Kharinov, Vladimir Zimovsky, Máté Krezinger
Publikováno v:
The Astronomical Journal, Vol 165, Iss 2, p 69 (2023)
Radio-loud quasars at high redshift ( z ≥ 4) are rare objects in the universe and rarely observed with Very Long Baseline Interferometry (VLBI). But some of them have flux density sufficiently high for monitoring of their apparent position. The ins
Externí odkaz:
https://doaj.org/article/5348dcfb94b84b5f87b69501d582e2b1
Autor:
Aletha de Witt, Christopher S. Jacobs, David Gordon, K-band Celestial Reference Frame Collaboration, Michael Bietenholz, Marisa Nickola, Alessandra Bertarini
Publikováno v:
The Astronomical Journal, Vol 165, Iss 4, p 139 (2023)
We present K -band (24 GHz) images of 731 compact extragalactic radio sources with submilliarcsecond resolution, based on radio interferometric observations made with the Very Long Baseline Array of 10 telescopes during 29 day long sessions spanning
Externí odkaz:
https://doaj.org/article/dab8e12208c546c59b62a9c3d9acae40
Publikováno v:
Universe, Vol 8, Iss 7, p 374 (2022)
Accurate measurement of angular positions on the sky requires a well-defined system of reference that is realized with accessible objects. The purpose of this study is to review the international standard realization of such a system, the Internation
Externí odkaz:
https://doaj.org/article/e204615142b346508ade9bb6b44b3921
Publikováno v:
South African Journal of Geomatics; Vol. 12 No. 1 (2023); 98-111
In the Very Long Baseline Interferometry (VLBI) space geodetic technique, various station-specific error sources corrupt the observable VLBI delay. An antenna axis offset (AO) model is applied in the VLBI data analysis for antennas with non-intersect
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::8c7054c1757f2cb9ce8cad61383fc8e7
https://www.ajol.info/index.php/sajg/article/view/242246
https://www.ajol.info/index.php/sajg/article/view/242246
Autor:
Tinus Stander, Dirk I. L. de Villiers, Aletha de Witt, Daniel Ferrusca Rodriquez, David Hiriart, Stanley E. Kurtz, Fanie van Den Heever, Miguel Velazquez de La Rosa Becerra
Publikováno v:
2022 International Conference on Electromagnetics in Advanced Applications (ICEAA).
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::99878fb0fd5f89c8096707808f4f8819
https://doi.org/10.1109/iceaa49419.2022.9899955
https://doi.org/10.1109/iceaa49419.2022.9899955
Autor:
Christopher S. Jacobs, Stanley E. Kurtz, Laurent Loinard, David H. Hughes, Aletha de Witt, Fanie van den Heever, Miguel Velázquez de la Rosa Becerra, Daniel Ferrusca Rodriguez, David Hiriart, Tinus Stander, William Cerfonteyn, Dirk I. L. de Villiers
Publikováno v:
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X.
The 50-meter Large Millimeter Telescope (LMT) operating on the Sierra Negra in Mexico is the largest single- dish millimeter-wave telescope in the world. Although designed to work in the 3 mm and 1 mm bands, there is significant potential for LMT obs
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::3d1e5eb6eeb048049ef89784222bf96f
https://doi.org/10.1117/12.2563132
https://doi.org/10.1117/12.2563132
Publikováno v:
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X.
The preliminary design and system simulation of an 18 - 45 GHz radio astronomy receiver is presented, planned for installation on the 26 m radio telescope at the Hartebeesthoek Radio Astronomy Observatory in South Africa. The receiver utilizes a side
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::d525390dfe46828888ec06d813aeed9b
https://doi.org/10.1117/12.2562026
https://doi.org/10.1117/12.2562026
Autor:
Fanie van den Heever, Tinus Stander, Stanley E. Kurtz, Daniel Ferrusca Rodriguez, Roger Deane, David Hiriart, Miguel Velázquez de la Rosa Becerra, Aletha de Witt, Dirk I. L. de Villiers
Publikováno v:
Ground-based and Airborne Telescopes VIII.
Water vapour radiometers (WVRs) are critical to both site surveying and site management in microwave and mm-wave very long baseline interferometry (VLBI). We report on the first two years of progress made towards improving the state of water vapour r
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::b77b2a3dae1952441c81bd9e707993b8
https://doi.org/10.1117/12.2562017
https://doi.org/10.1117/12.2562017
Autor:
Jay Blanchard, Carla Sharpe, Adrian Tiplady, Aletha de Witt, Ann Njeri, Robert Beswick, Melvin Hoare, Leonid I. Gurvits
Publikováno v:
Proceedings of the International Astronomical Union
Proceedings of the International Astronomical Union, 15
Proceedings of the International Astronomical Union, 15
Very Long Baseline Interferometry (VLBI) offers unrivalled resolution in studies of celestial radio sources. The subjects of interest of the IAU Symposium No. 356, the Active Galactic Nuclei (AGN) of all types, constitute the major observing sample o
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::9aad562defffd59d4983303001ef6763
http://arxiv.org/abs/2001.04576
http://arxiv.org/abs/2001.04576
