UvA-DARE Event Horizon Telescope observations of the jet launching and collimation in Centaurus A

25 microarcseconds ( μ as) at a wavelength ( λ ) of 1.3 mm. For a black hole mass of (5.5 ± 3) × 10 7 M ⊙ (ref. 7 ), we are probing jet structures down to scales of ~200 gravitational radii r g ≈ 0.6 light days. It has recently become possible to model these scales with sophis-ticated general relativistic magnetohydrodynamics (GRMHD) simulations 8 , where jet ejection and their symbiotic relationship with accretion flows are simulated from first principles. We have observed Cen A in a six-hour-long track on 10 April 2017. The EHT, as a novel and heterogeneous high-frequency very-long-baseline interferometry (VLBI) array, poses unique calibration challenges. To obtain robust results, independent of assumptions made during the data calibration, we base our scientific analysis on two datasets, which we obtained from two independent calibration pipelines: rPICARD 9 and EHT-HOPS 10 (‘Data reduction pipelines’ in Methods). Figure 1 presents our reconstruction of the jet image structure derived from the EHT data using a regularized maximum likelihood method, next to the large-scale source morphology and the