Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide.

  • Circulars are brief, citeable, and human-readable.
  • Circulars can announce observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans.
  • Circulars report on high-energy, multi-messenger, and variable or transient astrophysical events.

Circulars allow the GRB community to post messages (by email, or by submitting a web form) to a public list where they are distributed rapidly to the entire GRB community and archived permanently. These prose-style messages allow the community to coordinate and make optimum use of its limited resources.

For more details on how to use GCN Circulars, see:

  • Subscribing to receive GCN Circulars by email
  • Submitting to post your own GCN Circulars
  • Style Guide for how to write an effective GCN Circular
  • Corrections for how to make minor corrections to archived GCN Circulars
  • Archive for how to search for and browse GCN Circulars

Go to GCN Circulars Archive

Looking for U.S. government information and services? Visit