First Contact: Happens quite often. Not so much of a big thing these days for the Empire, who’ve really grown quite blasé about such things since that colonization mission discovered that Galáré was, oops, already inhabited back in the day, or other been-unbound-for-a-while star nations, but still the full-blown Very Big Deal for everyone who gets contacted by interstellar civilization.
It does have one interesting wrinkle: given the nature of the expansion of the wormhole nexus (see: Corralled Cosmos), by far the majority of first contacts are made by lighthugger starships operating outside it. Which is to say, by antimatter torchships decelerating into the contactee’s system. And a lighthugger’s antimatter torch is bright enough to be seen for at least the best part of a light-year. This unusual astronomical event has been known to have a few contact repercussions on its own, for which the traditional color-quote runs as follows:
“The Arrival was heralded, as the technology of relativistic starflight makes inevitable, by a new star in the sky, blue-white and baleful; fortunately, this being a modern and rational age on the planet below, no new religions were founded around this celestial oddity, and its appearance merely resulted in a socially acceptable level of rioting and apocalypse-cultism.”
And, not incidentally, means that sneaky first contacts and scouting around beforehand for whatever reason are really, really hard to pull off, assuming any level of technological civilization at all, really.