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We describe the process to design, architect, and implement a transformative enhancement of the Event Horizon Telescope (ngEHT). This program - the next-generation Event Horizon Telescope (ngEHT) - will form a networked global array of…

Space Very-Long-Baseline-Interferometry (S-VLBI) observations at high frequencies hold the prospect of achieving the highest angular resolutions and astrometric accuracies, resulting from the long baselines between ground and satellite…

Instrumentation and Methods for Astrophysics · Physics 2012-01-12 M. Rioja , R. Dodson , J. Malarecki , Y. Asaki

Recent developments in very long baseline interferometry (VLBI) have made it possible for the Event Horizon Telescope (EHT) to resolve the innermost accretion flows of the largest supermassive black holes on the sky. The sparse nature of…

We describe a new method which achieves high precision Very Long Baseline Interferometry (VLBI) astrometry in observations at millimeter wavelengths. It combines fast frequency-switching observations, to correct for the dominant…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 Maria J. Rioja , Richard Dodson

We have carried out full imaging simulation studies to explore the impact of frequency standards in millimeter and sub-millimeter Very Long Baseline Interferometry (VLBI), focusing on the coherence time and sensitivity. In particular, we…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 M. Rioja , R. Dodson , Y. Asaki , J. Hartnett , S. Tingay

The Event Horizon Telescope (EHT) is a millimeter-wavelength, very-long-baseline interferometry (VLBI) experiment that is capable of observing black holes with horizon-scale resolution. Early observations have revealed variable…

High Energy Astrophysical Phenomena · Physics 2016-12-20 Junhan Kim , Daniel P. Marrone , Chi-kwan Chan , Lia Medeiros , Feryal Özel , Dimitrios Psaltis

The Event Horizon Telescope (EHT), a global sub-millimeter wavelength very long baseline interferometry array, is now resolving the innermost regions around the supermassive black holes Sgr A* and M87. Using black hole images from both…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Angelo Ricarte , Jason Dexter

Horizon-scale imaging with the Event Horizon Telescope (EHT) has provided transformative insights into supermassive black holes but its resolution and scope are limited by ground-based constraints such as the size of the Earth, its…

Instrumentation and Methods for Astrophysics · Physics 2024-12-04 Yassine Ben Zineb , Feryal Ozel , Dimitrios Psaltis

The 2017 observing campaign of the Event Horizon Telescope (EHT) delivered the first very long baseline interferometry (VLBI) images at the observing frequency of 230 GHz, leading to a number of unique studies on black holes and…

High Energy Astrophysical Phenomena · Physics 2025-04-02 Jan Röder , Maciek Wielgus , Andrei P. Lobanov , Thomas P. Krichbaum , Dhanya G. Nair , Sang-Sung Lee , Eduardo Ros , Vincent L. Fish , Lindy Blackburn , Chi-kwan Chan , Sara Issaoun , Michael Janssen , Michael D. Johnson , Sheperd S. Doeleman , Geoffrey C. Bower , Geoffrey B. Crew , Remo P. J. Tilanus , Tuomas Savolainen , C. M. Violette Impellizzeri , Antxon Alberdi , Anne-Kathrin Baczko , José L. Gómez , Ru-Sen Lu , Georgios F. Paraschos , Efthalia Traianou , Ciriaco Goddi , Daewon Kim , Mikhail Lisakov , Yuri Y. Kovalev , Petr A. Voitsik , Kirill V. Sokolovsky , Kazunori Akiyama , Ezequiel Albentosa-Ruíz , Walter Alef , Juan Carlos Algaba , Richard Anantua , Keiichi Asada , Rebecca Azulay , Uwe Bach , David Ball , Mislav Baloković , Bidisha Bandyopadhyay , John Barrett , Michi Bauböck , Bradford A. Benson , Dan Bintley , Raymond Blundell , Katherine L. Bouman , Michael Bremer , Christiaan D. Brinkerink , Roger Brissenden , Silke Britzen , Avery E. Broderick , Dominique Broguiere , Thomas Bronzwaer , Sandra Bustamante , Do-Young Byun , John E. Carlstrom , Chiara Ceccobello , Andrew Chael , Dominic O. Chang , Koushik Chatterjee , Shami Chatterjee , Ming-Tang Chen , Yongjun Chen , Xiaopeng Cheng , Ilje Cho , Pierre Christian , Nicholas S. Conroy , John E. Conway , James M. Cordes , Thomas M. Crawford , Alejandro Cruz-Osorio , Yuzhu Cui , Brandon Curd , Rohan Dahale , Jordy Davelaar , Mariafelicia De Laurentis , Roger Deane , Jessica Dempsey , Gregory Desvignes , Jason Dexter , Vedant Dhruv , Indu K. Dihingia , Sean Taylor Dougall , Sergio A. Dzib , Ralph P. Eatough , Razieh Emami , Heino Falcke , Joseph Farah , Edward Fomalont , H. Alyson Ford , Marianna Foschi , Raquel Fraga-Encinas , William T. Freeman , Per Friberg , Christian M. Fromm , Antonio Fuentes , Peter Galison , Charles F. Gammie , Roberto García , Olivier Gentaz , Boris Georgiev , Roman Gold , Arturo I. Gómez-Ruiz , Minfeng Gu , Mark Gurwell , Kazuhiro Hada , Daryl Haggard , Kari Haworth , Michael H. Hecht , Ronald Hesper , Dirk Heumann , Luis C. Ho , Paul Ho , Mareki Honma , Chih-Wei L. Huang , Lei Huang , David H. Hughes , Shiro Ikeda , Makoto Inoue , David J. James , Buell T. Jannuzi , Britton Jeter , Wu Jiang , Alejandra Jiménez-Rosales , Svetlana Jorstad , Abhishek V. Joshi , Taehyun Jung , Mansour Karami , Ramesh Karuppusamy , Tomohisa Kawashima , Garrett K. Keating , Mark Kettenis , Dong-Jin Kim , Jae-Young Kim , Jongsoo Kim , Junhan Kim , Motoki Kino , Jun Yi Koay , Prashant Kocherlakota , Yutaro Kofuji , Shoko Koyama , Carsten Kramer , Joana A. Kramer , Michael Kramer , Cheng-Yu Kuo , Noemi La Bella , Tod R. Lauer , Daeyoung Lee , Po Kin Leung , Aviad Levis , Zhiyuan Li , Rocco Lico , Greg Lindahl , Michael Lindqvist , Jun Liu , Kuo Liu , Elisabetta Liuzzo , Wen-Ping Lo , Laurent Loinard , Colin J. Lonsdale , Amy E. Lowitz , Nicholas R. MacDonald , Jirong Mao , Nicola Marchili , Sera Markoff , Daniel P. Marrone , Alan P. Marscher , Iván Martí-Vidal , Satoki Matsushita , Lynn D. Matthews , Lia Medeiros , Karl M. Menten , Daniel Michalik , Izumi Mizuno , Yosuke Mizuno , James M. Moran , Kotaro Moriyama , Monika Moscibrodzka , Wanga Mulaudzi , Cornelia Müller , Hendrik Müller , Alejandro Mus , Gibwa Musoke , Ioannis Myserlis , Andrew Nadolski , Hiroshi Nagai , Neil M. Nagar , Masanori Nakamura , Gopal Narayanan , Iniyan Natarajan , Antonios Nathanail , Santiago Navarro Fuentes , Joey Neilsen , Roberto Neri , Chunchong Ni , Aristeidis Noutsos , Michael A. Nowak , Junghwan Oh , Hiroki Okino , Héctor R. Olivares Sánchez , Gisela N. Ortiz-León , Tomoaki Oyama , Feryal özel , Daniel C. M. Palumbo , Jongho Park , Harriet Parsons , Nimesh Patel , Ue-Li Pen , Dominic W. Pesce , Vincent Piétu , Richard Plambeck , Aleksandar PopStefanija , Oliver Porth , Felix M. Pötzl , Ben Prather , Jorge A. Preciado-López , Giacomo Principe , Dimitrios Psaltis , Hung-Yi Pu , Venkatessh Ramakrishnan , Ramprasad Rao , Mark G. Rawlings , Angelo Ricarte , Bart Ripperda , Freek Roelofs , Alan Rogers , Cristina Romero-Cañizales , Arash Roshanineshat , Helge Rottmann , Alan L. Roy , Ignacio Ruiz , Chet Ruszczyk , Kazi L. J. Rygl , Salvador Sánchez , David Sánchez-Argüelles , Miguel Sánchez-Portal , Mahito Sasada , Kaushik Satapathy , F. Peter Schloerb , Jonathan Schonfeld , Karl-Friedrich Schuster , Lijing Shao , Zhiqiang Shen , Des Small , Bong Won Sohn , Jason SooHoo , León David Sosapanta Salas , Kamal Souccar , Joshua S. Stanway , He Sun , Fumie Tazaki , Alexandra J. Tetarenko , Paul Tiede , Michael Titus , Pablo Torne , Teresa Toscano , Tyler Trent , Sascha Trippe , Matthew Turk , Ilse van Bemmel , Huib J. van Langevelde , Daniel R. van Rossum , Jesse Vos , Jan Wagner , Derek Ward-Thompson , John Wardle , Jasmin E. Washington , Jonathan Weintroub , Robert Wharton , Kaj Wiik , Gunther Witzel , Michael F. Wondrak , George N. Wong , Qingwen Wu , Nitika Yadlapalli , Paul Yamaguchi , Aristomenis Yfantis , Doosoo Yoon , André Young , Ken Young , Ziri Younsi , Wei Yu , Feng Yuan , Ye-Fei Yuan , J. Anton Zensus , Shuo Zhang , Guang-Yao Zhao , Shan-Shan Zhao

The transmission rate of communication between radio telescopes on Earth and extraterrestrial intelligence (ETI) is here calculated up to distances of 1000 light years. Both phase-shift-keying (PSK) and frequency-shift keying (FSK)…

Instrumentation and Methods for Astrophysics · Physics 2011-09-01 P. A. Fridman

The Event Horizon Telescope (EHT) provides a unique opportunity to probe the physics of supermassive black holes through Very Large Baseline Interferometry (VLBI), such as the existence of the event horizon, the accretion processes as well…

High Energy Astrophysical Phenomena · Physics 2018-12-12 Bidisha Bandyopadhyay , Dominik R. G. Schleicher , Neil Nagar , Fu-Guo Xie , Venkatessh Ramakrishnan

Global expansion of the Event Horizon Telescope (EHT) will see the strategic addition of antennas at new geographical locations, transforming the sensitivity and imaging fidelity of the $\lambda \sim 1$\,mm EHT array. A possible South…

Instrumentation and Methods for Astrophysics · Physics 2024-12-11 Senkhosi Simelane , Roger Deane , Athol Kemball , Roelf Botha , Roufurd Julie , Keitumetse Molamu , Adrian Tiplady , Aletha de Witt

The Event Horizon Telescope (EHT) is a very-long-baseline interferometry (VLBI) experiment that aims to observe supermassive black holes with an angular resolution that is comparable to the event horizon scale. The South Pole occupies an…

We demonstrate phase correction of 3 mm VLBI observations using the scanning 18 GHz to 26 GHz water vapour radiometer at Effelsberg and we demonstrate an absolute accuracy of 15 mm in zenith path delay by comparing with GPS and radiosondes.…

Astrophysics · Physics 2007-05-23 A. L. Roy , H. Rottmann , U. Teuber , R. Keller

Context. With the arrival of the next generation of ground-based imaging interferometers combining from 4 to possibly 6 telescopes simultaneously, there is also a strong need for a new generation of fringe trackers able to cophase such…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 N. Blind , O. Absil , J. -B. Lebouquin , J. -P. Berger , A. Chelli

Observing the dynamics of compact astrophysical objects provides insights into their inner workings, thereby probing physics under extreme conditions. The immediate vicinity of an active supermassive black hole with its event horizon,…

Instrumentation and Methods for Astrophysics · Physics 2022-06-07 Philipp Arras , Philipp Frank , Philipp Haim , Jakob Knollmüller , Reimar Leike , Martin Reinecke , Torsten Enßlin

High-resolution imaging of supermassive black holes is now possible, with new applications to testing general relativity and horizon-scale accretion and relativistic jet formation processes. Over the coming decade, the EHT will propose to…

Black hole imaging challenges the 3rd generation space VLBI, the Very Long Baseline Interferometry, to operate on a 500 GHz band. The coherent integration time needed here is 450 s though the available space oscillators cannot offer more…

Instrumentation and Methods for Astrophysics · Physics 2021-09-20 V. Kudriashov , M. Martin-Neira , E. Lia , J. Michalski , P. Kant , D. Trofimowicz , M. Belloni , P. Jankovic , P. Waller , M. Brandt

The Korean VLBI Network (KVN) is a new mm-VLBI dedicated array with capability for simultaneous observations at multiple frequencies, up to 129 GHz. The innovative multi-channel receivers present significant benefits for astrometric…

The Hilbert-Huang transform (HHT) consists of empirical mode decomposition (EMD), which is a template-free method that represents the combination of different intrinsic modes on a time-frequency map (i.e., the Hilbert spectrum). The…

Instrumentation and Methods for Astrophysics · Physics 2025-06-05 Lupin Chun-Che Lin , Chin-Ping Hu , Chien-Chang Yen , Kuo-Chuan Pan , C. Y. Hui , Kwan-Lok Li , Yu-Chiung Lin , Yi-Sheng Huang , Albert K. H. Kong