First M87 Event Horizon Telescope Results. III. Data Processing and Calibration

作者：Kazunori Akiyama, A. Alberdi, W. Alef, Keiichi Asada, Rebecca Azulay, Anne-Kathrin Baczko, David Ball, Mislav Baloković, John Barrett, Dan Bintley, Lindy Blackburn, W. Boland, Katherine L. Bouman, Geoffrey C. Bower, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, S. Britzen, Avery E. Broderick, Dominique Broguière, Thomas Bronzwaer, Do‐Young Byun, J. E. Carlstrom, Andrew Chael, Chi‐kwan Chan, Shami Chatterjee, Koushik Chatterjee, Ming‐Tang Chen, Xiaopeng Cheng, Ilje Cho, Pierre Christian, J. E. Conway, J. M. Cordes, G. Crew, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, G. Desvignes, Jason Dexter, Sheperd S. Doeleman, Ralph P. Eatough, H. Falcke, Vincent L. Fish, Ed Fomalont, Raquel Fraga-Encinas, Per Friberg, Christian M. Fromm, José L. Gómez, Peter Galison, Charles F. Gammie, Roberto García, Olivier Gentaz, Boris Georgiev, C. Goddi, Roman Gold, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, M. H. Hecht, Ronald Hesper, Luis C. Ho, Paul T. P. Ho, Mareki Honma, Chih-Wei L. Huang, Lei 磊 Huang 黄, D. H. Hughes, Shiro Ikeda, Makoto Inoue, Sara Issaoun, D. J. James, Buell T. Jannuzi, Michaël Janssen, Britton Jeter, Wu Jiang, Michael D. Johnson, Svetlana G. Jorstad, Taehyun Jung, Mansour Karami, R. Karuppusamy, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Jae-Young Kim, Junhan Kim, Jongsoo Kim, Motoki Kino, Jun Yi Koay, Patrick M. Koch, Shoko Koyama, Michael Kramer, C. Krämer, T. P. Krichbaum, Cheng‐Yu Kuo, Tod R. Lauer, Sang-Sung Lee, Yanrong Li, Zhiyuan 志远 Li 李, M. Lindqvist, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, A. P. Lobanov, Laurent Loinard, C. J. Lonsdale, Ru-Sen Lu, Nicholas R. MacDonald, Jirong 基荣 Mao 毛, Sera Markoff, Daniel P. Marrone, Alan P. Marscher, I. Martí‐Vidal, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, K. M. Menten, Yosuke Mizuno, Izumi Mizuno, J. M. Moran, Kotaro Moriyama, Monika Mościbrodzka, Cornelia Müller, Hiroshi Nagai, Neil M. Nagar, Masanori Nakamura, Ramesh Narayan, Gopal Narayanan, Iniyan Natarajan, R. Neri, Chunchong Ni, A. Noutsos, Hiroki Okino, Héctor Olivares, Gisela N. Ortiz-León, Tomoaki Oyama, Feryal Özel, Daniel C. M. Palumbo, Nimesh Patel, Ue‐Li Pen, Dominic W. Pesce, Vincent Piétu, R. L. Plambeck, Aleksandar PopStefanija, Oliver Porth, Ben Prather, Jorge A. Preciado-López, Dimitrios Psaltis, Hung-Yi Pu, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Alexander W. Raymond, Luciano Rezzolla, Bart Ripperda, Freek Roelofs, A. E. E. Rogers, E. Ros, Mel Rose, Arash Roshanineshat, Helge Rottmann, A. L. Roy, Chet Ruszczyk, Benjamin R. Ryan, K. L. J. Rygl, Salvador Sánchez, David Sánchez-Argüelles, Mahito Sasada, T. Savolainen, F. Peter Schloerb, K. Schüster, Lijing Shao, Zhi-Qiang Shen, Des Small, Bong Won Sohn, Jason Soohoo, Fumie Tazaki, Paul Tiede, R. P. J. Tilanus, Michael Titus, Kenji Toma, Pablo Torné, Tyler Trent, Sascha Trippe, Shuichiro Tsuda, Ilse van Bemmel, Huib Jan van Langevelde, Daniel R. van Rossum, Jan Wagner, J. F. C. Wardle, Jonathan Weintroub, Norbert Wex, Robert Wharton, Maciek Wielgus, George N. Wong, Qingwen 庆文 Wu 吴, André Young, Ken Young, Ziri Younsi, Feng 峰 Yuan 袁, Ye-Fei 业飞 Yuan 袁, J. A. Zensus, Guang-Yao Zhao, Shan-Shan Zhao, Ziyan Zhu, R. J. Cappallo, Joseph Farah, Thomas W. Folkers, Zheng Meyer-Zhao, Daniel Michalik, Andrew Nadolski, Hiroaki Nishioka, Nicolas Pradel, Rurik A. Primiani, Kamal Souccar, Laura Vertatschitsch, Paul Yamaguchi · 发表于：The Astrophysical Journal Letters · 年份：2019 · DOI：10.3847/2041-8213/ab0c57 · 被引用次数：883 · 研究领域：Radio Astronomy Observations and Technology、Astrophysical Phenomena and Observations、Astrophysics and Cosmic Phenomena

Abstract We present the calibration and reduction of Event Horizon Telescope (EHT) 1.3 mm radio wavelength observations of the supermassive black hole candidate at the center of the radio galaxy M87 and the quasar 3C 279, taken during the 2017 April 5–11 observing campaign. These global very long baseline interferometric observations include for the first time the highly sensitive Atacama Large Millimeter/submillimeter Array (ALMA); reaching an angular resolution of 25 μ as, with characteristic sensitivity limits of ∼1 mJy on baselines to ALMA and ∼10 mJy on other baselines. The observations present challenges for existing data processing tools, arising from the rapid atmospheric phase fluctuations, wide recording bandwidth, and highly heterogeneous array. In response, we developed three independent pipelines for phase calibration and fringe detection, each tailored to the specific needs of the EHT. The final data products include calibrated total intensity amplitude and phase information. They are validated through a series of quality assurance tests that show consistency across pipelines and set limits on baseline systematic errors of 2% in amplitude and 1° in phase. The M87 data reveal the presence of two nulls in correlated flux density at ∼3.4 and ∼8.3 G λ and temporal evolution in closure quantities, indicating intrinsic variability of compact structure on a timescale of days, or several light-crossing times for a few billion solar-mass black hole. These measurements pr...