High-resolution observations of high-redshift ($z>4$) radio quasars offer a unique insight into jet kinematics at early cosmological epochs, as well as constraints on cosmological model parameters. Due to the general weakness of extremely distant objects and the apparently slow structural changes caused by cosmological time dilation, only a couple of high-redshift quasars have been studied with parsec-scale resolutions, and with limited number of observing epochs. Here we report on very long baseline interferometry (VLBI) observations of a high-redshift blazar J1430 + 4204 ($z=4.72$) in the 8 GHz frequency band at five different epochs spanning 22 years. The source shows a compact core–jet structure with two jet components being identified within 3 milli-arcsecond (mas) scale. The long time span and multiple-epoch data allow for the kinematic studies of the jet components. That results in a jet proper motion of $\mu (\mathrm{J}1)$ = 0.017 ± 0.002 mas ${\mathrm{yr}}^{-1}$ and $\mu (\mathrm{J}2)$ = 0.156 ± 0.015 mas ${\mathrm{yr}}^{-1}$, respectively. For the fastest-moving outer jet component J2, the corresponding apparent transverse speed is $19.5\pm 1.9c$. The inferred bulk jet Lorentz factor $\mathrm{\Gamma }=14.6\pm 3.8$ and viewing angle $\theta =2.2°\pm 1.6°$ indicate highly relativistic beaming. The Lorentz factor and apparent proper motion are the highest measured to date among the $z>4$ jetted radio sources, while the jet kinematics is still consistent with the cosmological interpretation of quasar redshifts.

高红移的高分辨率观测（$z>\mathrm{4个}$)射电类星体提供了对早期宇宙学时期喷流运动学的独特见解，以及对宇宙学模型参数的限制。由于极远天体的普遍弱点和宇宙时间膨胀引起的明显缓慢的结构变化，只有几个高红移类星体以秒差距分辨率进行了研究，并且观测时间有限。在这里，我们报告了对高红移耀变体 J1430 + 4204（$z=4.72$) 在跨越 22 年的五个不同时期的 8 GHz 频段中。来源显示了一个紧凑的核心射流结构，在 3 毫角秒 (mas) 尺度内识别出两个射流组件。长时间跨度和多时期数据允许对射流部件进行运动学研究。这导致射流自行$\mu (\mathrm{杰}\mathrm{1个})$ = 0.017 ± 0.002 质量 ${\mathrm{年}}^{-\mathrm{1个}}$和$\mu (\mathrm{杰}\mathrm{2个})$ = 0.156 ± 0.015 质量 ${\mathrm{年}}^{-\mathrm{1个}}$， 分别。对于移动最快的外射流分量 J2，相应的表观横向速度为$19.5\pm 1.9C$. 推断的散装射流洛伦兹因子$\mathrm{\Gamma }=14.6\pm 3.8$和视角$\theta =2.2°\pm 1.6°$表示高度相对论的光束。洛伦兹因子和视自行是迄今为止测得的最高值$z>\mathrm{4个}$喷射射电源，而喷射运动学仍然与类星体红移的宇宙学解释一致。