Skip to main content
New GCN Circulars features for September 2023! 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').
  1. Untitled
  2. Untitled
  3. Untitled
  4. Untitled
  5. Untitled
  6. Untitled
  7. Untitled
  8. Untitled
  9. Untitled
  10. Untitled
  11. Untitled
  12. Untitled
  13. Untitled
  14. Untitled
  15. Untitled
  16. Untitled
  17. Untitled
  18. Untitled
  19. Untitled
  20. Untitled
  21. Untitled
  22. Untitled
  23. Untitled
  24. Untitled
  25. Untitled
  26. Untitled
  27. Untitled
  28. Untitled
  29. Untitled
  30. Untitled
  31. Untitled
  32. Untitled
  33. Untitled
  34. Untitled
  35. Untitled

Advanced

Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

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