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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"

30 results found.

  1. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  2. GRB 211211A: observations with the 3.6m Devasthal Optical Telescope
  3. GRB 211211A: MMT/MMIRS Observations Indicate Fading of K-band Source
  4. GRB 211211A: TNG NIR observations
  5. GRB 211211A: Insight-HXMT/HE detection
  6. GRB 211211A - Gemini K-band detection
  7. GRB 211211A: SAO RAS optical observations
  8. GRB 211211A: AbAO optical observations
  9. GRB 211211A: GMG upper limit
  10. GRB 211211A: redshift estimation and SPI-ACS/INTEGRAL detection
  11. GRB 211211A: Very fast decay observed from CAFOS/2.2mCAHA
  12. GRB 211211A: Further observations from CAFOS/2.2m CAHA
  13. GRB 211211A: HCT and GIT optical follow up observations
  14. GRB 211211A: CALET Gamma-Ray Burst Monitor detection
  15. GRB 211211A: incorrect E_iso value in GCN 31221
  16. GRB 211211A: Swift/UVOT detection
  17. GRB 211211A: NOT optical spectroscopy
  18. GRB 211211A: Afterglow detection from CAFOS/2.2m CAHA
  19. GRB 211211A: MITSuME Akeno optical observation
  20. Swift GRB 211211A: Global MASTER-Net observations report
  21. GRB 211211A: LCO Optical Observations
  22. GRB 211211A: Nanshan/NEXT optical observations
  23. GRB 211211A: Swift-XRT refined Analysis
  24. GRB 211211A: Fermi GBM observation
  25. GRB 211211A: Swift-BAT refined analysis
  26. Fermi GRB 211211A: Global MASTER-Net observations report
  27. GRB 211211A: Enhanced Swift-XRT position
  28. GRB 211211A: KAIT Optical Afterglow Candidate
  29. GRB 211211A: Swift detection of a bright burst
  30. GRB 211211A: Fermi GBM Final Real-time Localization

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