Gravity Sensors

The only type of passive sensors that are capable of working in hyperspace, with thermal working barely and only in areas of very low spatial compression rate. In the very same time it is also a passive sensor system that works ONLY in hyperspace. They are based on very important rule of hyperspace, which makes its gravity fluctuate permanently. Ships and other stable objects are more permanent in terms of gravity, with their stability making the gravity fields around them more stable. This allows gravity sensors to detect ships and other objects by detecting surprisingly calm points in their surroundings.
The range of detection is next to pathetic when compared to thermal sensors in Realspace. Besides finding out that there are potential hostiles nearby is only a first step. Then you have to narrow down their location, which requires a multiple gravitational sensors (which means - ships) to work together and triangulate areas where gravitation is most calm. Which is reason for creation of both convoys and wolf packs, since otherwise they wouldn't be able to find each other. And then you have to start firing your artillery more or less towards the place you expect enemy to be, hoping that one of your shots will connect (or coming even closer, using automatic drones or smaller ships to locate enemies with targeting lasers or thermal sensors from shortest possible ranger, rarely bigger than 100 000km. Which makes every shot to connect deadly.