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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"

25 results found.

  1. GRB 250920C: TERI Gamma-ray detection
  2. GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
  3. GRB 250920C: Kilonova-Catcher optical afterglow detection
  4. GRB 250920C: TRT optical observation
  5. Konus-Wind detection of GRB 250920C
  6. GRB 250920C: KAIT optical observations
  7. GRB 250920C: VLT redshift confirmation z = 1.399
  8. GRB 250920C: SALT redshift confirmation
  9. GRB 250920C: COLIBRÍ optical observations
  10. GRB 250920C: NIR observations with WINTER
  11. GRB 250920C: PRIME near-infrared detection
  12. GRB 250920C: Swift-XRT refined Analysis
  13. GRB 250920C: SVOM/GRM observation
  14. GRB 250920C: GTC/OSIRIS+ spectroscopic redshift z = 1.40
  15. GRB 250920C: GROWTH-India Telescope optical observations
  16. GRB 250920C: Swift-BAT refined analysis
  17. GRB 250920C: Enhanced Swift-XRT position
  18. GRB 250920C: Swift/UVOT Detection
  19. GRB 250920C: Fermi GBM Observation
  20. Swift GRB 250920C: Global MASTER-Net observations report
  21. GRB 250920C: Optical counterpart detection by LCO
  22. GRB250920C: LCOGT Optical Detection
  23. GRB 250920C: GOTO optical counterpart candidate
  24. GRB 250920C: Swift detection of a burst
  25. GRB 250920C: Fermi GBM Final Real-time Localization

Advanced

Download all Circulars as a .tar.gz archive:
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