It’s mentioned in this article: https://www.syfy.com/syfywire/is-this-cosmic-sprinkler-surrounding-galaxys-next-gamma-ray-burst https://www.syfy.com/syfywire/is

It’s mentioned in this article: https://www.syfy.com/syfywire/is-this-cosmic-sprinkler-surrounding-galaxys-next-gamma-ray-burst https://www.syfy.com/syfywire/is-this-cosmic-sprinkler-surro... . My impression is that a GRB beam is on the order of a few degrees, but I can’t find that reference now.