First off, to all of my Rush fan readers (Alan, I'm looking at you in particular), this is not about either of the Cygnus X-1 songs. Sorry.
Actually, what I'm going to talk about is much cooler. It started when I came across a Tweet from the Astronomer's Telegram (@astronomerstel) which led to a "telegram" titled "Cygnus X-1 is entering its hard X-ray state". Of course, these are no longer actual telegrams. Rather, they are shared public messages from astronomers telling other astronomers that something exciting is happening in space and that people should point the appropriate telescopes at it.