Coma Berenices (Coma Ber), an open cluster about the same age as Praesepe and the Hyades (700–800 Myr) is, despite being only 85 pc away, less well studied than its famous cousins. This is due principally to its sparseness and low proper motion, which together made Coma Ber’s membership challenging to establish pre-Gaia. We have curated a new list of its members based on Gaia DR2 astrometry, derived its metallicity and interstellar reddening using LAMOST data, and inferred the cluster’s age by fitting PARSEC isochrones to its color–magnitude diagram. We then measured rotation periods for Coma Ber’s low-mass members using TESS and ZTF photometry. Our isochrone fitting and the TESS- and ZTF-derived rotation periods confirm that Coma Ber is coeval with the Hyades and Praesepe. This work is the first step toward re-establishing Coma Ber as another valuable benchmark cluster for age–rotation–activity studies.

Coma Berenices (Coma Ber) 是一个与 Praesepe 和 Hyades (700–800 Myr) 年龄相近的疏散星团，尽管距离它只有 85 pc，但其研究不如其著名的表亲。这主要是由于它的稀疏性和低自行，这共同使得 Coma Ber 的成员难以建立前盖亚。我们根据 Gaia DR2 天体测量法整理了一份新的成员名单，使用 LAMOST 数据推导出了它的金属丰度和星际红化，并通过将 PARSEC 等时线拟合到它的颜色-星等图来推断星团的年龄。然后，我们使用 TESS 和 ZTF 光度法测量了 Coma Ber 的低质量成员的旋转周期。我们的等时线拟合以及 TESS 和 ZTF 衍生的旋转周期证实了 Coma Ber 与 Hyades 和 Praesepe 是同时代的。