• DOI:10.3847/2041-8213/ab0c57
• Corpus ID: 115150503

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

@article{Akiyama2019FirstME,
  title={First M87 Event Horizon Telescope Results. III. Data Processing and Calibration},
  author={Kazunori Akiyama and Antxon Alberdi and Walter Alef and Keiichi Asada and Rebecca Azulay and Anne-Kathrin Baczko and David Ball and Mislav Balokovi{\'c} and John Barrett and Dan Bintley and Lindy L. Blackburn and Wilfred Boland and Katherine L. Bouman and Geoffrey C. Bower and Michael Bremer and Christiaan D. Brinkerink and Roger Brissenden and Silke Britzen and Avery E. Broderick and Dominique Broguiere and Thomas Bronzwaer and Do-young Byun and John E. Carlstrom and Andrew Chael and Chi-kwan Chan and Shami Chatterjee and Koushik Chatterjee and Ming-Tang Chen and Yongjun 永 军 Chen 陈 and Ilje Cho and Pierre Christian and John E. Conway and James M. Cordes and Geoffrey B. Crew and Yuzhu Cui and Jordy Davelaar and Mariafelicia De Laurentis and Roger Deane and Jessica Dempsey and Gregory Desvignes and Jason Dexter and Sheperd S. Doeleman and Ralph P. Eatough and Heino Falcke and Vincent L. Fish and Edward B. Fomalont and Raquel Fraga-Encinas and Per Friberg and Christian M. Fromm and Jos{\'e} L. G{\'o}mez and Peter Galison and Charles F. Gammie and Roberto Garc{\'i}a and Olivier Gentaz and Boris Georgiev and Ciriaco Goddi and Roman Gold and Minfeng 敏峰 Gu 顾 and Mark A. Gurwell and Kazuhiro Hada and Michael H. Hecht and Ronald Hesper and Luis C. 子山 Ho 何 and Paul T. P. Ho and Mareki Honma and Chih-Wei L. Huang and Lei 磊 Huang 黄 and David H. Hughes and Shiro Ikeda and Makoto Inoue and Sara Issaoun and David J. James and Buell T. Jannuzi and Michael Janssen and Britton Jeter and Wu 悟 Jiang 江 and Michael D. Johnson and Svetlana G. Jorstad and Taehyun Jung and Mansour Karami and Ramesh Karuppusamy and Tomohisa Kawashima and Garrett K. Keating and Mark Kettenis and Jae-Young Kim and Junhan Kim and Jongsoo Kim and Motoki Kino and Jun Yi Koay and Patrick M. Koch and Shoko Koyama and Michael Kramer and Carsten Kramer and Thomas P. Krichbaum and C. Y. Kuo and Tod R. Lauer and Sang-Sung Lee and Yan-Rong 彦荣 Li 李 and Zhiyuan 志远 Li 李 and Michael Lindqvist and Kuo Liu and Elisabetta Liuzzo and W. Lo and Andrei P. Lobanov and Laurent Loinard and Colin J. Lonsdale and Ru-Sen 如森 Lu 路 and Nicholas R. MacDonald and Jirong 基荣 Mao 毛 and Sera B. Markoff and Daniel P. Marrone and Alan P. Marscher and Iv{\'a}n Mart{\'i}-Vidal and Satoki Matsushita and Lynn D. Matthews and Lia Medeiros and Karl M. Menten and Yosuke Mizuno and Izumi Mizuno and James M. Moran and Kotaro Moriyama and Monika A. Mościbrodzka and Cornelia M{\"u}ller and Hiroshi Nagai and Neil M. Nagar and Masanori Nakamura and Ramesh Narayan and Gopal Narayanan and Iniyan Natarajan and Roberto Neri and Chunchong Ni and Aristeidis Noutsos and Hiroki Okino and H{\'e}ctor Olivares and Gisela N. Ortiz-L{\'e}on and Tomoaki Oyama and Feryal {\"O}zel and Daniel C. M. Palumbo and Nimesh A. Patel and Ue-li Pen and Dominic W. Pesce and Vincent Pi{\'e}tu and Richard L. Plambeck and Aleksandar PopStefanija and Oliver Porth and Ben S. Prather and Jorge A. Preciado-L{\'o}pez and Dimitrios Psaltis and Hung-Yi Pu and Venkatessh Ramakrishnan and Ramprasad Rao and Mark G. Rawlings and Alexander W. Raymond and Luciano Rezzolla and Bart Ripperda and Freek Roelofs and Alan E. E. Rogers and Eduardo Ros and Mel Rose and Arash Roshanineshat and Helge Rottmann and Alan L. Roy and Chester A. Ruszczyk and Benjamin R. Ryan and Kazi L. J. Rygl and Salvador S{\'a}nchez and David S{\'a}nchez-Arguelles and Mahito Sasada and Tuomas Savolainen and F. P. Schloerb and Karl F. Schuster and Lijing Shao and Zhiqiang 志强 Shen 沈 and Des Small and Bong Won Sohn and Jason SooHoo and Fumie Tazaki and Paul Tiede and Remo P. J. Tilanus and Michael Titus and Kenji Toma and Pablo Torne and Tyler Trent and Sascha Trippe and Shuichi Tsuda and Ilse M. van Bemmel and Huib Jan van Langevelde and Daniel R. van Rossum and Jan Wagner and J. F. C. Wardle and Jonathan Weintroub and Norbert Wex and Robert S. Wharton and Maciek Wielgus and George N. Wong and Qingwen 庆文 Wu 吴 and Andr{\'e} Young and K. H. Young and Ziri Younsi and Feng 峰 Yuan 袁 and Ye-Fei 业 飞 Yuan 袁 and J. Anton Zensus and Guangyao Zhao and Shan-Shan Zhao and Ziyan Zhu and Roger C. Cappallo and Joseph R. Farah and Thomas W. Folkers and Z. Meyer-Zhao and Daniel Michalik and Andrew Nadolski and Hiroaki Nishioka and Nicolas Pradel and Rurik A. Primiani and Kamal Souccar and Laura Vertatschitsch and Paul Yamaguchi},
  journal={The Astrophysical Journal Letters},
  year={2019},
  volume={875}
}

• K. Akiyama, A. Alberdi, +214 authors P. Yamaguchi
• Published 10 April 2019
• Physics
• The Astrophysical Journal Letters

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.