<P> In surveys of globular clusters , these `` cluster - type '' variables were being rapidly identified in the mid-1890s , especially by E.C. Pickering . </P>
<P> In surveys of globular clusters , these `` cluster - type '' variables were being rapidly identified in the mid-1890s , especially by E.C. Pickering . </P>
who first used rr lyrae variable stars to determine distances in our milky way galaxy
who first used rr lyrae variable stars to determine distances in our milky way galaxy
E.C. Pickering
E.C. Pickering