The GCN system distributes:
These two functions provide a one-stop shopping network for follow-up sites
and GRB and transient researchers.
Locations of GRBs and other Transients (the Notices) detected by spacecraft (most in real-time while the burst is still bursting and
others are that delayed due to telemetry down-link delays).
Reports of follow-up observations (the Circulars and the Reports) made by
ground-based and space-based optical, radio, x-ray, TeV, and other particle observers.
The GCN system can be explored using the links above and below.
Invitation to subscribe to the GCN/TAN here.
The physical GCN network. (Click to enlarge.)