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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"

33 results found.

  1. GRB 251222A: SVOM/ECLAIRs refined analysis
  2. GRB 251222A: radio detection with the VLA
  3. GRB 251222A: Mondy Optical Observations
  4. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  5. GRB 251222A: NUTTelA-TAO Early Measurements
  6. GRB 251222A/EP251222b: Optical detection with Kinder observations
  7. GRB 251222A/EP251222b: FTW optical and NIR observations
  8. GRB 251222A: AbAO optical observations
  9. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  10. GRB 251222A: ZTSH BVRI optical observations
  11. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  12. GRB 251222A: Continued 1.3m DFOT optical observation
  13. GRB 251222A: Fermi GBM Observation
  14. GRB 251222A / EP251222b: GECAM-B observation
  15. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  16. Konus-Wind detection of GRB 251222A / EP251222b
  17. GRB 251222A: Swift-XRT afterglow detection
  18. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  19. GRB 251222A / EP251222b: GOTO optical counterpart detection
  20. GRB 251222A / EP251222b: LCO optical observations
  21. GRB 251222A: 1.3m DFOT optical detection
  22. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  23. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  24. EP251222b/GRB 251222A: SVOM/GRM observation
  25. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  26. GRB 251222A: PRIME near-infrared detection
  27. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  28. GRB 251222A: NOT optical observations
  29. GRB 251222A: Swift ToO observations
  30. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  31. GRB 251222A: SVOM/VT optical candidate
  32. GRB 251222A: SVOM detection of a long burst
  33. GRB 251222A: Fermi GBM Final Real-time Localization

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