Can anyone say with certainty what type of beacon

[AzuredreamsXT]

The slug cruiser unlock event is at? Is it the ship detected beacon?

[MushrooMars]

I'm not particularly sure, but I think any slug ship that says "We will offer you what'sss in our storessss for our livesss." is a valid chance to get the Slug Cruiser.

I might be wrong however; I've only had one bloody playthrough in which a Slug Home Nebula was generated, even then, my first two encounters in the Home Nebula were pimped out Auto-Scouts (which killed me).

[AzuredreamsXT]

I followed my hunch and went after an out of the way ship detected beacon (long range scanners) near the start of the sector. It was a slug ship that offered the event when defeated.

I definitely recommend getting long range scanners when hunting for unlock events. If you know what to look for (ordinary beacon for stealth cruiser, ship detected beacon for slug etc) you can narrow down the number of beacons you need to check, this improving your shot at finding the event before the rebels run you out of the sector.