However, there are some interesting terms you could use to describe groups of astronomers or astronomical objects:
For groups of astronomers:
* Constellation (this is a bit metaphorical, as it refers to a group of stars, but it could work for a group of astronomers who are collaborating on a project).
* Observatory (this refers to a place where astronomers work, but it could also be used to describe a group of astronomers gathered at a particular observatory).
* Conference (a specific type of group, but it could be used to describe a gathering of astronomers).
For groups of astronomical objects:
* Galaxy (for a group of stars, gas, dust, and planets)
* Cluster (for a group of stars, galaxies, or other objects)
* Constellation (for a group of stars that form a recognizable pattern in the sky)
* Nebula (for a cloud of gas and dust)
* Solar System (for a group of planets, moons, asteroids, and comets that orbit a star)
Ultimately, the best collective noun to use will depend on the specific context. You could also be creative and come up with your own!