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. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').

8 results found.

  1. GRB 111121A: Suzaku WAM observation of the prompt emission
  2. Konus-Wind observation of GRB 111121A
  3. GRB 111121A: Swift/UVOT Upper Limits
  4. GRB 111121A: Magellan/Megacam observations
  5. GRB 111121A: Swift-XRT refined Analysis
  6. GRB 111121A: Swift-BAT refined analysis
  7. GRB 111121A: Enhanced Swift-XRT position
  8. GRB 111121A: Swift detection of a short hard burst


Download all Circulars as a .tar.gz archive:
Looking for U.S. government information and services? Visit