Why is this Sleeper visible?

There isn't much context in the screenshot, but this is all that came to mind:
1. You traced the hack that created the sleeper, but you voluntarily let the hack finish. (Inferred from this post.)
2. You clicked the Sleeper Identification button on the system, spending a small amount of Influence. This button appears after researching Mineral Manipulation.
3. You hacked the owner's primary system and selected the Infiltrate Scanners option to see everything they see. (Only a guess since Diplomatic Vision Sharing doesn't show sleepers.)