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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"

21 results found.

  1. GRB 250430A / EP250430a: AstroSat CZTI detection
  2. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  3. GRB 250430A: Swift-BAT refined analysis
  4. GRB 250430A: Swift-XRT refined Analysis
  5. GRB 250430A: Swift/UVOT Detection
  6. GRB 250430A: Enhanced Swift-XRT position
  7. GRB 250430A: Optical Observations via Virtual Telescope Project, Italy
  8. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  9. GRB 250430A: SVOM/VT optical observations
  10. GRB 250430A: KAIT optical observations
  11. GRB 250430A / EP250430a: J-band upper limits with WINTER
  12. GRB 250430A: NUTTelA-TAO Early Measurements
  13. GRB 250430A: DDOTI Optical Observations
  14. GRB 250430A: Leavitt Observatory optical upper limit
  15. GRB 250430A: Bassano Bresciano Observatory upper limit
  16. GRB 250430A : MITSuME Akeno optical upper limits
  17. GRB 250430A / EP250430a: VLT/X-shooter spectroscopic redshift z = 0.767
  18. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  19. GRB 250430A: AKO Optical Afterglow Detection
  20. GRB 250430A: Kanata optical upper limit
  21. GRB 250430A: Swift detection of a burst with optical counterpart

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