Measurements of the center-of-mass energies of collisions at BESIII

During the 2016-17 and 2018-19 running periods, the BESIII experiment collected 7.5 fb $ ^{-1} $ of $ ^{-1} $ collision data at center-of-mass energies ranging from 4.13 to 4.44 GeV. These data samples are primarily used for the study of excited charmonium and charmoniumlike states. By analyzing the di-muon process $ ^{-1} $ $ ^{-1} $ , we measure the center-of-mass energies of the data samples with a precision of 0.6 MeV. Through a run-by-run study, we find that the center-of-mass energies were stable throughout most of the data-collection period.