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Review

Overview and Status of the International Celestial Reference Frame as Realized by VLBI

1
South African Radio Astronomy Observatory (SARAO), P.O. Box 443, Krugersdorp 1740, South Africa
2
Laboratoire d’astrophysique de Bordeaux, Université de Bordeaux, CNRS, B18N, Allée Geoffroy Saint-Hilaire, 33615 Pessac, France
3
U.S. Naval Observatory, 3450 Massachusetts Ave NW, Washington, DC 20392, USA
4
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Academic Editor: Xue-Mei Deng
Universe 2022, 8(7), 374; https://doi.org/10.3390/universe8070374
Received: 14 May 2022 / Revised: 16 June 2022 / Accepted: 28 June 2022 / Published: 7 July 2022
(This article belongs to the Special Issue VLBI Science Applications)
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 International Celestial Reference Frame (ICRF). The ICRF uses the Very Long Baseline Interferometry (VLBI) technique as it has the highest resolution of any current astrometric technique for reference frames in order to observe Active Galactic Nuclei (AGN) which are at such great distances (typical redshift ∼1) that there is currently no observed parallax or proper motion of these objects thus giving the frame excellent stability. We briefly review the history of the transition from the Fundamental Katalog 5 (FK5) optical frame to VLBI-based frames with attention to each of the three generations: ICRF-1, ICRF-2, and ICRF-3. We present some of the more prominent applications of the ICRF and outline the methods used to construct the ICRF. Next we discuss in more detail the current standard ICRF-3—which is the first frame to be realized at multiple wavelengths (S/X, K, X/Ka-bands)—including an estimate of its accuracy and limiting errors. We conclude with an overview of future plans for improving the ICRF. View Full-Text
Keywords: radio interferometry; astrometry; active galactic nuclei; ICRF radio interferometry; astrometry; active galactic nuclei; ICRF
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MDPI and ACS Style

de Witt, A.; Charlot, P.; Gordon, D.; Jacobs, C.S. Overview and Status of the International Celestial Reference Frame as Realized by VLBI. Universe 2022, 8, 374. https://doi.org/10.3390/universe8070374

AMA Style

de Witt A, Charlot P, Gordon D, Jacobs CS. Overview and Status of the International Celestial Reference Frame as Realized by VLBI. Universe. 2022; 8(7):374. https://doi.org/10.3390/universe8070374

Chicago/Turabian Style

de Witt, Aletha, Patrick Charlot, David Gordon, and Christopher S. Jacobs. 2022. "Overview and Status of the International Celestial Reference Frame as Realized by VLBI" Universe 8, no. 7: 374. https://doi.org/10.3390/universe8070374

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