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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"

19140 results found.

  1. GRB050117: MASTER optical observations
  2. MASTER:GRB050117 SWIFT
  3. GRB050117: Swift-BAT detection of a long multi-peaked burst
  4. GRB050117: Swift XRT Position
  5. SGR1806-20: Swift-BAT observations of two additional bursts
  6. SGR 1806-20, RHESSI observations of the 041227 giant flare
  7. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  8. GRB 041217: Optical observations
  9. SGR1806-20: Swift-BAT observation of the 041227 super-flare
  10. GRB041228: ROTSE-III Optical Observations
  11. GRB041228: Swift-BAT detection of a burst
  12. GRB041219; RXTE ASM Observations
  13. NIR Observations of GRB 041219
  14. GRB041226: ROTSE-III Optical Observations
  15. GRB041226: Swift-BAT detection of a burst
  16. GRB041223: decay of the afterglow
  17. GRB041224: ROTSE-III Optical Observations
  18. GRB 041223: XRT afterglow spectrum and light curve
  19. GRB 041223 Fluence measured by Swift-BAT
  20. GRB041224: Swift-BAT detection of a soft burst
  21. GRB041223: optical and NIR observations with REM
  22. Swift-BAT Time History of GRB041219
  23. GRB041223: Swift XRT Detection of X-ray Afterglow Emission
  24. GRB041223: ROTSE-III Optical Observations
  25. GRB041223: Swift-BAT detection of a bright long burst
  26. GRB041220: Swift-BAT burst
  27. GRB 041219 Optical Observations
  28. GRB041219c: Third Burst in One Day from Swift-BAT
  29. GRB041219b: A Swift-BAT burst
  30. Swift-BAT detection of the bright long burst GRB041219
  31. GRB041217: optical limit 30 min after GRB
  32. GRB041217: Optical Observations
  33. GRB041217: NIR and optical observations with REM
  34. GRB041217: P60 Optical Observations
  35. GRB041217: Infrared Observations
  36. GRB041217: The First GRB Located On-Board Swift
  37. GRB040916: Optical observations
  38. GRB040422: optical and NIR observations at the VLT
  39. GRB040223, improved XMM position
  40. SN 2003jd (SN/GRB?) - possible association with GRB 030929

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