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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.

Advanced Search Examples (click to copy):

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

22 results found.

  1. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  2. GRB 250506A: NOT optical upper limits
  3. GRB 250506A: GECAM detection
  4. GRB 250506A: Swift-XRT afterglow detection
  5. GRB 250506A: SVOM/VT optical upper limit
  6. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 250506A: Swift/UVOT Upper Limits
  8. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  9. GRB 250506A: Swift-XRT observations
  10. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  11. GRB 250506A: Mephisto optical upper limits
  12. GRB 250506A: Swift ToO observations
  13. IceCube-250506A - IceCube observation of a high-energy neutrino candidate track-like event
  14. GRB 250506A: Xinglong 2.16m optical upper limit
  15. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  16. GRB 250506A: REM optical/NIR upper limits
  17. GRB 250506A: Fermi GBM Observation
  18. GRB 250506A: Swift XRT observations and possible counterpart detection
  19. GRB 250506A: TRT optical observations
  20. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  21. GRB 250506A: SVOM detection of a burst
  22. GRB 250506A: Fermi GBM Final Real-time Localization

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Download all Circulars as a .tar.gz archive:
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