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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"

11 results found.

  1. GRB 241218A: Mondy AZT-33IK optical upper limit
  2. GRB 241218A: Swift/UVOT Upper Limits
  3. GRB 241218A: NOT optical upper limits
  4. GRB 241218A: Swift-BAT refined analysis
  5. GRB 241218A: REM optical upper limit
  6. GRB 241218a: Liverpool Telescope optical follow-up
  7. GRB 241218A: Swift-XRT refined Analysis
  8. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  9. GRB 241218A: LCOGT Optical Upper Limit
  10. GRB 241218A: Enhanced Swift-XRT position
  11. GRB 241218A: Swift detection of a burst

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Download all Circulars as a .tar.gz archive:
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