Hologram

Investigation of the unrecognized fleet signatures in the … system revealed an unexpected discovery. The fleet is not, in fact, in safe orbit of the black hole, but rather crossing its event horizon. Science Officer … conjectures that the fleet approached …'s event horizon centuries ago, whereupon time dilation left their image detectable on its surface. Whether the fleet's actions were intentional, or the result of some unhappy accident, we may never know. Their signatures match no known civilization on record.

The command below will trigger the "Hologram" event in Stellaris:

When this event fires, you can choose between the following option:

• Curious.
  • Add deposit: +3

Stellaris events fire in chains — one event leads to the next. Here is how Hologram (distar.20) connects.