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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"

16 results found.

  1. GRB 251001B: Swift-BAT refined analysis
  2. GRB 251001B: Swift/UVOT Detection
  3. GRB 251001B: COLIBRÍ optical observations
  4. GRB 251001B: GTC/OSIRIS+ spectroscopic redshift z = 2.162
  5. GRB 251001B: Swift-XRT refined Analysis
  6. GRB 251001B: SVOM/VT optical observation
  7. GRB 251001B: NOT optical observations
  8. Swift GRB 251001B: Global MASTER-Net observations report
  9. GRB 251001B: Fermi GBM Observation
  10. GRB 251001B: Further GOTO observations of optical counterpart.
  11. GRB 251001B: Enhanced Swift-XRT position
  12. GRB 251001B: LCOGT Optical Observations
  13. GRB 251001B: TRT optical afterglow detection and potential host galaxy
  14. GRB 251001B: GOTO optical counterpart detection
  15. GRB 251001B: Swift detection of a burst
  16. GRB 251001B: Fermi GBM Final Real-time Localization

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Download all Circulars as a .tar.gz archive:
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