Public Data Release of the Event Horizon Telescope 2017 Observations

The Event Horizon Telescope Collaboration (EHTC) and Joint ALMA Observatory (JAO) announce the public data release of the Very Long Baseline Interferometry (VLBI) 1-mm observations by the Event Horizon Telescope (EHT) in April 2017. The overall goal of the observations is to image the supermassive black holes M 87* and Sagittarius A* at event horizon scales and to image the AGNs OJ 287, 3C 279, Centaurus A, and NGC 1052 at high resolution.

Public release data packages are available from CyVerse Data Commons (DOI: 10.25739/kat4-na03) and the ALMA Science Portal.

This data delivery contains what is defined by the EHTC as L1 data for the 2017 observing campaign. The 2017 campaign was the first where the Atacama Large Millimeter Array (ALMA) participated as a phased array, a capability that was developed by the ALMA Phasing Project. The EHT L1 data encompasses the VLBI correlator output, converted into circular polarization basis, as well as the calibration information from the participating telescopes. For ALMA this includes their quality assurance (QA2) output that is used for the polarization basis conversion. The primary reference for the data from the EHT 2017 observing campaign is EHTC et al. 2019, ApJL, 875, L3 (DOI: 10.3847/2041-8213/ab0c57), which in detail discusses the processing carried out for the current L1 data delivery. For scientific results derived from the EHT 2017 observing campaign, see Additional data products derived from this L1 data can be found at

This data delivery includes observations from the following facilities: ALMA, the Atacama Pathfinder Experiment (APEX), the Submillimeter Telescope (SMT), the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope Alfonso Serrano (LMT), the IRAM 30m telescope, the Submillimeter Array (SMA), and the South Pole Telescope (SPT). More information about these facilities can be found in EHTC et al. 2019, ApJL, 875, L2 (DOI: 10.3847/2041-8213/ab0c96).

Project codes:

 Sagittarius A* (SGRA)  2016.1.01404.V
 M 87* (M87)  2016.1.01154.V
 OJ 287 (OJ287)  2016.1.01114.V
 3C 279 (3C279)  2016.1.01176.V
 Centaurus A (CENA)  2016.1.01198.V
 NGC 1052 (NGC1052)  2016.1.01290.V