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').

14 results found.

  1. GRB 230510A: Swift-BAT refined analysis
  2. GRB 230510A: GRBAlpha detection
  3. GRB 230510A: OHP/T193 and OHP/T120 optical observations
  4. GRB 230510A: GIT optical upper limits
  5. GRB 230510A: LCOGT Optical Upper Limit
  6. GRB 230510A: Swift/UVOT Observations
  7. GRB 230510A: Fermi GBM detection
  8. GRB 230510A: Gaoyazi/GOT optical upper limit
  9. GRB 230510A: CALET Gamma-Ray Burst Monitor detection
  10. GRB 230510A: Nanshan/NEXT optical afterglow detection
  11. GRB 230510A: Swift-XRT refined Analysis
  12. GRB 230510A: Enhanced Swift-XRT position
  13. GRB 230510A: Swift detection of a burst
  14. GRB 230510A: Fermi GBM Final Real-time Localization


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