Observations by Hubble’s Advanced Camera for Surveys spotted 29 dwarf elliptical galaxies in the Perseus Cluster located 250 million light-years away and one of the closest galaxy clusters to Earth.
哈勃使用先进的观测镜头对英仙座中29个椭圆状矮星系进行了观察，这些星系属于距离地球最近的星系团之一，约2.5亿光年远。
This paper discusses cluster sampling and stratified cluster sampling in continuous surveys with censuses.
本文讨论了连续调查中应用普查方法时的整群抽样和分层整群抽样。
Observations by Hubble's Advanced Camera for Surveys spotted 29 dwarf elliptical galaxies in the Perseus cluster located 250 million light-years away and one of the closest galaxy clusters to Earth.
哈勃使用先进的观测镜头对英仙座中29个椭圆状矮星系进行了观察，这些星系属于距离地球最近的星系团之一，约2.5亿光年远。
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