First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multiwavelength Observations, Data Processing, and Calibration
Date Issued
2022
Author(s)
Event Horizon Telescope Collaboration
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Akiyama, Kazunori
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Alberdi, Antxon
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Alef, Walter
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Algaba, Juan Carlos
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Anantua, Richard
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Asada, Keiichi
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Azulay, Rebecca
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Bach, Uwe
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Baczko, Anne-Kathrin
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Ball, David
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Baloković, Mislav
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Barrett, John
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Bauböck, Michi
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Benson, Bradford A.
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Bintley, Dan
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Blackburn, Lindy
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Blundell, Raymond
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Bouman, Katherine L.
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Bower, Geoffrey C.
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Boyce, Hope
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Bremer, Michael
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Brinkerink, Christiaan D.
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Brissenden, Roger
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Britzen, Silke
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Broderick, Avery E.
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Broguiere, Dominique
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Bronzwaer, Thomas
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Bustamante, Sandra
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Byun, Do-Young
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Carlstrom, John E.
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Ceccobello, Chiara
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Chael, Andrew
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Chan, Chi-kwan
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Chatterjee, Koushik
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Chatterjee, Shami
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Chen, Ming-Tang
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Chen, Yongjun
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Cheng, Xiaopeng
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Cho, Ilje
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Christian, Pierre
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Conroy, Nicholas S.
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Conway, John E.
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Cordes, James M.
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Crawford, Thomas M.
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Crew, Geoffrey B.
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Cruz-Osorio, Alejandro
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Cui, Yuzhu
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Davelaar, Jordy
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De Laurentis, Mariafelicia
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Deane, Roger
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Dempsey, Jessica
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Desvignes, Gregory
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Dexter, Jason
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Dhruv, Vedant
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Doeleman, Sheperd S.
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Dougal, Sean
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Dzib, Sergio A.
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Eatough, Ralph P.
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Emami, Razieh
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Falcke, Heino
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Farah, Joseph
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Fish, Vincent L.
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Fomalont, Ed
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Ford, H. Alyson
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Fraga-Encinas, Raquel
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Freeman, William T.
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Friberg, Per
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Fromm, Christian M.
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Fuentes, Antonio
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Galison, Peter
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Gammie, Charles F.
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García, Roberto
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Gentaz, Olivier
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Georgiev, Boris
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Goddi, Ciriaco
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Gold, Roman
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Gómez-Ruiz, Arturo I.
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Gómez, José L.
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Gu, Minfeng
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Gurwell, Mark
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Hada, Kazuhiro
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Haggard, Daryl
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Haworth, Kari
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Hecht, Michael H.
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Hesper, Ronald
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Heumann, Dirk
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Ho, Luis C.
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Ho, Paul
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Honma, Mareki
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Huang, Chih-Wei L.
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Huang, Lei
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Hughes, David H.
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Ikeda, Shiro
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Impellizzeri, C. M. Violette
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Inoue, Makoto
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Issaoun, Sara
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James, David J.
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Jannuzi, Buell T.
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Janssen, Michael
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Jeter, Britton
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Jiang, Wu
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Jiménez-Rosales, Alejandra
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Johnson, Michael D.
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Jorstad, Svetlana
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Joshi, Abhishek V.
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Jung, Taehyun
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Karami, Mansour
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Karuppusamy, Ramesh
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Kawashima, Tomohisa
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Keating, Garrett K.
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Kettenis, Mark
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Kim, Dong-Jin
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Kim, Jae-Young
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Kim, Jongsoo
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Kim, Junhan
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Kino, Motoki
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Koay, Jun Yi
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Kocherlakota, Prashant
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Kofuji, Yutaro
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Koch, Patrick M.
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Koyama, Shoko
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Kramer, Carsten
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Kramer, Michael
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Krichbaum, Thomas P.
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Kuo, Cheng-Yu
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Lauer, Tod R.
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Lee, Daeyoung
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Lee, Sang-Sung
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Leung, Po Kin
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Levis, Aviad
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Li, Zhiyuan
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Lindahl, Greg
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Lindqvist, Michael
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Lisakov, Mikhail
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Liu, Jun
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Liu, Kuo
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Lo, Wen-Ping
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Lobanov, Andrei P.
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Loinard, Laurent
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Lonsdale, Colin J.
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Lu, Ru-Sen
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Mao, Jirong
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Markoff, Sera
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Marrone, Daniel P.
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Marscher, Alan P.
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Martí-Vidal, Iván
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Matsushita, Satoki
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Matthews, Lynn D.
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Medeiros, Lia
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Menten, Karl M.
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Michalik, Daniel
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Mizuno, Izumi
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Mizuno, Yosuke
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Moran, James M.
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Moriyama, Kotaro
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Moscibrodzka, Monika
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Müller, Cornelia
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Mus, Alejandro
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Musoke, Gibwa
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Myserlis, Ioannis
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Nadolski, Andrew
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Nagai, Hiroshi
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Nagar, Neil M.
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Nakamura, Masanori
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Narayan, Ramesh
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Narayanan, Gopal
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Natarajan, Iniyan
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Nathanail, Antonios
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Fuentes, Santiago Navarro
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Neilsen, Joey
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Neri, Roberto
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Ni, Chunchong
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Noutsos, Aristeidis
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Nowak, Michael A.
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Oh, Junghwan
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Okino, Hiroki
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Olivares, Héctor
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Ortiz-León, Gisela N.
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Oyama, Tomoaki
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Özel, Feryal
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Palumbo, Daniel C. M.
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Paraschos, Georgios Filippos
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Park, Jongho
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Parsons, Harriet
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Patel, Nimesh
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Pen, Ue-Li
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Pesce, Dominic W.
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Piétu, Vincent
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Plambeck, Richard
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PopStefanija, Aleksandar
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Porth, Oliver
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Pötzl, Felix M.
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Prather, Ben
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Preciado-López, Jorge A.
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Psaltis, Dimitrios
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Pu, Hung-Yi
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Ramakrishnan, Venkatessh
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Rao, Ramprasad
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Rawlings, Mark G.
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Raymond, Alexander W.
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Rezzolla, Luciano
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Ricarte, Angelo
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Ripperda, Bart
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Roelofs, Freek
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Rogers, Alan
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Ros, Eduardo
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Romero-Cañizales, Cristina
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Roshanineshat, Arash
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Rottmann, Helge
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Roy, Alan L.
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Ruiz, Ignacio
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Ruszczyk, Chet
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Sánchez, Salvador
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Sánchez-Argüelles, David
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Sánchez-Portal, Miguel
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Sasada, Mahito
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Satapathy, Kaushik
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Savolainen, Tuomas
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Schloerb, F. Peter
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Schonfeld, Jonathan
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Schuster, Karl-Friedrich
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Shao, Lijing
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Shen, Zhiqiang
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Small, Des
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Sohn, Bong Won
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SooHoo, Jason
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Souccar, Kamal
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Sun, He
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Tazaki, Fumie
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Tetarenko, Alexandra J.
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Tiede, Paul
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Tilanus, Remo P. J.
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Titus, Michael
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Torne, Pablo
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Traianou, Efthalia
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Trent, Tyler
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Trippe, Sascha
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Turk, Matthew
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van Bemmel, Ilse
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van Langevelde, Huib Jan
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van Rossum, Daniel R.
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Vos, Jesse
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Wagner, Jan
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Ward-Thompson, Derek
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Wardle, John
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Weintroub, Jonathan
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Wex, Norbert
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Wharton, Robert
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Wielgus, Maciek
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Wiik, Kaj
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Witzel, Gunther
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Wondrak, Michael F.
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Wong, George N.
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Wu, Qingwen
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Yamaguchi, Paul
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Yoon, Doosoo
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Young, André
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Young, Ken
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Younsi, Ziri
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Yuan, Feng
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Yuan, Ye-Fei
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Zensus, J. Anton
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Zhang, Shuo
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Zhao, Guang-Yao
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Zhao, Shan-Shan
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Agurto, Claudio
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Araneda, Juan Pablo
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Arriagada, Oriel
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Bertarini, Alessandra
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Berthold, Ryan
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Blanchard, Jay
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Brown, Ken
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Cárdenas, Mauricio
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Cantzler, Michael
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Caro, Patricio
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Chuter, Tim C.
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Ciechanowicz, Miroslaw
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Coulson, Iain M.
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Crowley, Joseph
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Degenaar, Nathalie
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Dornbusch, Sven
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Durán, Carlos A.
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Forster, Karl
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Geertsema, Gertie
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González, Edouard
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Graham, Dave
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Gueth, Frédéric
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Han, Chih-Chiang
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Herrera, Cristian
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Herrero-Illana, Ruben
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Heyminck, Stefan
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Hoge, James
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Huang, Yau-De
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Jiang, Homin
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John, David
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Klein, Thomas
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Kubo, Derek
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Kuroda, John
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Kwon, Caleb
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Laing, Robert
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Liu, Ching-Tang
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Liu, Kuan-Yu
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Mac-Auliffe, Felipe
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Martin-Cocher, Pierre
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Matulonis, Callie
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Messias, Hugo
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Meyer-Zhao, Zheng
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Montenegro-Montes, Francisco
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Montgomerie, William
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Muders, Dirk
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Nishioka, Hiroaki
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Norton, Timothy J.
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Olivares, Rodrigo
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Pérez-Beaupuits, Juan Pablo
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Parra, Rodrigo
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Poirier, Michael
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Pradel, Nicolas
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Raffin, Philippe A.
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Ramírez, Jorge
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Reynolds, Mark
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Saez-Madain, Alejandro F.
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Santana, Jorge
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Silva, Kevin M.
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Sousa, Don
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Stahm, William
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Torstensson, Karl
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Venegas, Paulina
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Walther, Craig
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Wieching, Gundolf
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Wijnands, Rudy
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Wouterloot, Jan G. A.
Abstract
We present Event Horizon Telescope (EHT) 1.3 mm measurements of the radio source located at the position of the supermassive black hole Sagittarius A* (Sgr A*), collected during the 2017 April 5-11 campaign. The observations were carried out with eight facilities at six locations across the globe. Novel calibration methods are employed to account for Sgr A*'s flux variability. The majority of the 1.3 mm emission arises from horizon scales, where intrinsic structural source variability is detected on timescales of minutes to hours. The effects of interstellar scattering on the image and its variability are found to be subdominant to intrinsic source structure. The calibrated visibility amplitudes, particularly the locations of the visibility minima, are broadly consistent with a blurred ring with a diameter of ~50 μas, as determined in later works in this series. Contemporaneous multiwavelength monitoring of Sgr A* was performed at 22, 43, and 86 GHz and at near-infrared and X-ray wavelengths. Several X-ray flares from Sgr A* are detected by Chandra, one at low significance jointly with Swift on 2017 April 7 and the other at higher significance jointly with NuSTAR on 2017 April 11. The brighter April 11 flare is not observed simultaneously by the EHT but is followed by a significant increase in millimeter flux variability immediately after the X-ray outburst, indicating a likely connection in the emission physics near the event horizon. We compare Sgr A*'s broadband flux during the EHT campaign to its historical spectral energy distribution and find that both the quiescent emission and flare emission are consistent with its long-term behavior.
Volume
930
Issue
2
Start page
L13
Issn Identifier
2041-8205
Ads BibCode
2022ApJ...930L..13E
Rights
open.access
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