First M87 Event Horizon Telescope results. III. Data processing and calibration
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Akiyama, Kazunori
Alberdi, Antxon
Alef, Walter
Asada, Keiichi
Azulay, Rebecca
Baczko, Anne-Kathrin
Ball, David
Baloković, Mislav
Barrett, John
Bintley, Dan
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Kazunori Akiyama, Antxon Alberdi, Walter Alef, Keiichi Asada, Rebecca Azulay, Anne-Kathrin Baczko, David Ball, Mislav Baloković, John Barrett, Dan Bintley, Lindy Blackburn, Wilfred Boland, Katherine L Bouman, Geoffrey C Bower, Michael Bremer, Christiaan D Brinkerink, Roger Brissenden, Silke Britzen, Avery E Broderick, Dominique Broguiere, Thomas Bronzwaer, Do-Young Byun, John E Carlstrom, Andrew Chael, Chi-kwan Chan, Shami Chatterjee, Koushik Chatterjee, Ming-Tang Chen, Yongjun Chen, Ilje Cho, Pierre Christian, John E Conway, James M Cordes, Geoffrey B Crew, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, Gregory Desvignes, Jason Dexter, Sheperd S Doeleman, Ralph P Eatough, Heino 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, Ciriaco Goddi, Roman Gold, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Michael H Hecht, Ronald Hesper, Luis C Ho, Paul Ho, Mareki Honma, Chih-Wei L Huang, Lei Huang, David H Hughes, Shiro Ikeda, Makoto Inoue, Sara Issaoun, David J James, Buell T Jannuzi, Michael Janssen, Britton Jeter, Wu Jiang, Michael D Johnson, Svetlana Jorstad, Taehyun Jung, Mansour Karami, Ramesh 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, Carsten Kramer, Thomas P Krichbaum, Cheng-Yu Kuo, Tod R Lauer, Sang-Sung Lee, Yan-Rong Li, Zhiyuan Li, Michael Lindqvist, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, Andrei P Lobanov, Laurent Loinard, Colin Lonsdale, Ru-Sen Lu, Nicholas R MacDonald, Jirong Mao, Sera Markoff, Daniel P Marrone, Alan P Marscher, Iván Martí-Vidal, Satoki Matsushita, Lynn D Matthews, Lia Medeiros, Karl M Menten, Yosuke Mizuno, Izumi Mizuno, James M Moran, Kotaro Moriyama, Monika Moscibrodzka, Cornelia Müller, Hiroshi Nagai, Neil M Nagar, Masanori Nakamura, Ramesh Narayan, Gopal Narayanan, Iniyan Natarajan, Roberto Neri, Chunchong Ni, Aristeidis Noutsos, Hiroki Okino, Héctor Olivares, Gisela N Ortiz-León, Tomoaki Oyama, Feryal Özel, Daniel CM Palumbo, Nimesh Patel, Ue-Li Pen, Dominic W Pesce, Vincent Piétu, Richard 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, Alan Rogers, Eduardo Ros, Mel Rose, Arash Roshanineshat, Helge Rottmann, Alan L Roy, Chet Ruszczyk, Benjamin R Ryan, Kazi LJ Rygl, Salvador Sánchez, David Sánchez-Arguelles, Mahito Sasada, Tuomas Savolainen, F Peter Schloerb, Karl-Friedrich Schuster, Lijing Shao, Zhiqiang Shen, Des Small, Bong Won Sohn, Jason SooHoo, Fumie Tazaki, Paul Tiede, Remo PJ Tilanus, Michael Titus, Kenji Toma, Pablo Torne, Tyler Trent, Sascha Trippe, Shuichiro Tsuda, Ilse van Bemmel, Huib Jan van Langevelde, Daniel R van Rossum, Jan Wagner, John Wardle, Jonathan Weintroub, Norbert Wex, Robert Wharton, Maciek Wielgus, George N Wong, Qingwen Wu, André Young, Ken Young, Ziri Younsi, Feng Yuan, Ye-Fei Yuan, J Anton Zensus, Guangyao Zhao, Shan-Shan Zhao, Ziyan Zhu, Roger Cappallo, Joseph R Farah, Thomas W Folkers, Zheng Meyer-Zhao, Daniel Michalik, Andrew Nadolski, Hiroaki Nishioka, Nicolas Pradel, Rurik A Primiani, Kamal Souccar, Laura Vertatschitsch, Paul Yamaguchi. "First M87 Event Horizon Telescope Results. III. Data Processing and Calibration." The Astrophysical Journal, Volume 875, Issue 1, pp. L3 - L3. https://doi.org/10.3847/2041-8213/ab0c57
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 μas, 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 Gλ 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 provide the first opportunity to image horizon-scale structure in M87.
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