How do I build nebula refinery? I can't tell which system have nebula?

[Coocoodas]

Is there an indicator on the map or something?

[Stormsong]

Nebulae are cloudy blotches of space in the galaxy map which are named. If you're having trouble seeing the clouds, look for the random regions of space that have names. In the system view, look for the blue thundercloud by the system's nametag at the bottom. This is a positive system effect. In a nebula's case, people can't see what's going on inside unless they are inside the system. That effect is largely useless vs. AI though.

[EleventhStar]

its part of the tooltip of star systems on the galaxy map (i think neutron stars and blackholes etc have a speciall tooltip too if you want to see what it looks like). you can also see stuff like "xyz nebula" or "abc dustcloud" written on the map if you explored enough to give a bit of a clue of where to look. but yeah its not the easiest thing to find.

supposedly nebulas/dust clouds also block sensors, so you could find em that way too i guess but sensor range is even harder to figure out.

another way them is to look for resources that only spawn inside nebulas, but afaik that is only zro.

[Hazel]

There are splashes of colour with names over them on the galaxy. These are nebulae, and any systems within can host a refinery. Also, they're slower to move through and IIRC sensors can't see through them very well.

[Coocoodas]

Thanks guys! Found it.