Sirius is unpredictable. No one may tell, what wil you find befond peaceful, especially in clouds, old warmade graveyard or area with high radiation.
If you have enough bravery to leave your own comfortable zone, you have chance to find broken, locked or sealed. Sometimes their storage might contain something useful and adventurers, researchers, pirates or just random traders can explore and gather information.
Basic information:
Event is timeless and timezone doesn't really matter, so everyone may chance to get reward
All derelicts aren't arranged in unfair area. They may be below or above the plain, but still in scan range
Every loot you found there is yours, no one will limit you
All bases may be under RP assetment, so if you strongly need to catch base in your hands, don't hesitate to ask.
Also keep in mind, all derelicts aren't lifeless, their support and providing rewards takes a time and hard work to keep event active.