A comment on this question ham.stackexchange.com/q/2001/4476 says to "check the cluster". What does it mean to "check the cluster"? I'm guessing it's a website. I did an internet search and hamcluster.net/Map.aspx seems to be limited to DX

@YetAnotherRandomUser That would be a really good question to ask, because we don't have it already! "I got a suggestion to check 'the cluster' for propagation information. What is this, where can I find it, and how is it useful for propagation?"