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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').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Lucene Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

24 results found.

  1. GRB 250327B: VIRT Optical Upper Limit
  2. GRB 250327B: Swift/UVOT Detection
  3. GRB 250327B: Kilonova-Catcher Observations
  4. Konus-Wind detection of GRB 250327B
  5. GRB20250327B: 45th Parallel Observatory upper limit
  6. GRB 250327B: ALMA detection
  7. GRB 250327B: VLA detection
  8. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  9. GRB 250327B: J-band observations with WINTER
  10. GRB 250327B: MASTER detection of OT rebrightening
  11. GRB 250327B: LCO optical counterpart detection
  12. GRB 250327B: CrAO and SAO RAS Optical Observations
  13. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  14. GRB 250327B: further optical observations by LCOGT
  15. GRB 250327b: Liverpool Telescope optical observations
  16. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  17. GRB 250327B: Las Cumbres optical counterpart detection
  18. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  19. GRB 250327B: 1.6m Mephisto optical observations
  20. GRB 250327B: NOT spectroscopic redshift z = 3.035
  21. GRB 250327B: GOTO optical counterpart detection
  22. GRB 250327B: SVOM/VT optically bright counterpart
  23. GRB 250327B: SAO RAS optical candidate
  24. GRB 250327B: SVOM detection of a burst

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Download all Circulars as a .tar.gz archive:
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