Skip to main content
New Swift-BAT/GUANO and IceCube Notice Types Available! 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').

9 results found.

  1. KAIT Optical Upper Limits for GRB 120422A, 120724A, 120803B, 120911A, and 120923A
  2. GRB 120803B: Swift-XRT refined Analysis
  3. Erratum of subject line of GCN13570 (GRB 120803A => GRB 120803B)
  4. GRB 120803B: MITSuME Okayama Optical upper limits
  5. GRB 120803B: Swift-BAT refined analysis
  6. GRB 120803B: Enhanced Swift-XRT position
  7. GRB 120803B: MITSuME Akeno Optical upper limits
  8. GRB 120803B: FTN possible afterglow candidate
  9. GRB 120803B: Swift detection of a burst


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