We present the UV photometry of the old open cluster NGC188 obtained using images acquired with Ultraviolet Imaging Telescope (UVIT) on board the AstroSat satellite, in two far-UV (FUV) and one near-UV (NUV) filters. UVIT data is utilised in combination with optical photometric data to construct the optical and UV colour-magnitude diagrams (CMDs). In the FUV images, we detect only hot and bright blue straggler stars (BSSs), one hot subdwarf, and one white dwarf (WD) candidate. In the NUV images, we detect members up to a faintness limit of \(\sim 22\) mag including 21 BSSs, 2 yellow straggler stars (YSSs), and one WD candidate. This study presents the first NUV-optical CMDs, and are overlaid with updated BaSTI-IAC isochrones and WD cooling sequence, which are found to fit well to the observed CMDs. We use spectral energy distribution (SED) fitting to estimate the effective temperatures, radii, and luminosities of the UV-bright stars. We find the cluster to have an HB population with three stars (\(T_{{\mathrm{eff}}} = 4750\)–21000 K). We also detect two yellow straggler stars, with one of them with UV excess connected to its binarity and X-ray emission.

我们展示了旧疏散星团 NGC188 的紫外光度测量，使用 AstroSat 卫星上的紫外成像望远镜 (UVIT) 获得的图像，在两个远紫外 (FUV) 和一个近紫外 (NUV) 过滤器中。UVIT 数据与光学光度数据结合使用，以构建光学和 UV 色阶图 (CMD)。在 FUV 图像中，我们只检测到炽热明亮的蓝色落后星 (BSS)、一颗炽热亚矮星和一颗白矮星 (WD) 候选星。在 NUV 图像中，我们检测到模糊极限为\(\sim 22\)mag 包括 21 颗 BSS、2 颗黄色落后星 (YSS) 和 1 颗 WD 候选星。这项研究展示了第一个 NUV 光学 CMD，并与更新的 BaSTI-IAC 等时线和 WD 冷却序列重叠，发现它们与观察到的 CMD 非常吻合。我们使用光谱能量分布 (SED) 拟合来估计紫外线明亮恒星的有效温度、半径和光度。我们发现该星团具有三颗星的 HB 群体（\(T_{{\mathrm{eff}}} = 4750\) –21000 K）。我们还探测到两颗黄色的落伍星，其中一颗的紫外线过量与它的二元性和 X 射线发射有关。