Skip to main content
Introducing Einstein Probe, Astro Flavored Markdown, and Notices Schema v4.0.0. 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').

10 results found.

  1. GRB 150301B: Swift-XRT refined Analysis
  2. GRB 150301B: Swift/UVOT Observations
  3. GRB 150301B: LCOGT-Sutherland observations
  4. GRB 150301B: Fermi GBM detection
  5. GRB 150301B: Swift-BAT refined analysis
  6. GRB 150301B: X-shooter spectroscopy
  7. GRB 150301B: GROND afterglow observations
  8. GRB 150301B: Enhanced Swift-XRT position
  9. GRB 150301B: MASTER early OT detection
  10. GRB 150301B: Swift detection of a burst with an optical afterglow


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