We use data from the ESA Gaia mission Early Data Release 3 (EDR3) to measure the trigonometric parallax of ω Cen, the first high-precision parallax measurement for the most massive globular cluster in the Milky Way. We use a combination of positional and high-quality proper motion data from EDR3 to identify over 100,000 cluster members, of which 67,000 are in the magnitude and color range where EDR3 parallaxes are best calibrated. We find the estimated parallax to be robust, demonstrating good control of systematics within the color–magnitude diagram of the cluster. We find a parallax for the cluster of 0.191 0.001 (statistical) 0.004 (systematic) mas (2.2% total uncertainty) corresponding to a distance of 5.24 0.11 kpc. The parallax of ω Cen provides a unique opportunity to directly and geometrically calibrate the luminosity of the tip of the red giant branch (TRGB) because it is the only cluster with sufficient mass to provide enough red giant stars, more than 100 one magnitude below the tip, for a precise, model-free measurement of the tip. Combined with the preexisting and most widely used measurements of the tip and foreground Milky Way extinction, we find M _I,TRGB =−3.97 0.06 mag for the I-band luminosity of the blue edge. Using the TRGB luminosity calibrated from the Gaia EDR3 parallax of ω Cen to calibrate the luminosity of Type Ia supernovae results in a value for the Hubble constant of H ₀ = 72.1 2.0 km s⁻¹ Mpc⁻¹. We make the data for the stars in ω Cen available electronically and encourage independent analyses of the results presented here.

我们使用来自 ESA Gaia 任务早期数据发布 3 (EDR3) 的数据来测量ω Cen的三角视差，这是对银河系中质量最大的球状星团的首次高精度视差测量。我们结合使用来自 EDR3 的位置和高质量自行数据来识别超过 100,000 个集群成员，其中 67,000 个位于 EDR3 视差最佳校准的幅度和颜色范围内。我们发现估计的视差是稳健的，表明在集群的颜色幅度图中可以很好地控制系统学。我们发现集群的视差为 0.191 0.001（统计）0.004（系统）mas（2.2% 总不确定性）对应于 5.24 0.11 kpc 的距离。ω的视差Cen 提供了一个独特的机会来直接和几何校准红巨星分支 (TRGB) 尖端的光度，因为它是唯一具有足够质量的星团，可以提供足够的红巨星，比尖端以下一个星等 100 多颗，用于尖端的精确、无模型测量。结合先前存在和最广泛使用的尖端和前景银河系消光测量，我们发现蓝色边缘的I波段光度为M _{I ,TRGB} =−3.97 0.06 mag 。使用从ω Cen的 Gaia EDR3 视差校准的 TRGB 光度来校准 Ia 型超新星的光度导致哈勃常数值H ₀ = 72.1 2.0 km s ^-1 Mpc ^-1。我们以电子方式提供ω Cen 中恒星的数据，并鼓励对此处呈现的结果进行独立分析。