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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"

36801 results found.

  1. Fermi GBM Detection of a weak source
  2. GRB 090408B: MASTER II-Kourovka optical observations
  3. GRB 090408: Swift detection of a burst
  4. GRB 090407: GROND upper limits
  5. GRB 090407: VLT observations
  6. GRB 090407: Swift-XRT refined analysis
  7. GRB 090407: Swift UVOT Upper Limits
  8. GRB 090407: Enhanced Swift-XRT position
  9. GRB 090407: Swift-BAT refined analysis
  10. Konus-Wind and Konus-RF observations of GRB 090406
  11. GRB 090407: ROTSE-III Optical Limits
  12. GRB 090407: Swift detection of a burst
  13. GRB 090404: millimeter detection
  14. GRB 090404: nIR observations at Calar Alto
  15. GRB 090405: Fermi GBM Detection
  16. GRB 090403: Fermi GBM detection
  17. GRB 090404: GROND upper limits
  18. GRB 090404: further NOT observations
  19. Swift/UVOT observations of GRB090404
  20. GRB 090404: NOT observations
  21. GRB 090404: optical observations at BOOTES-3 and 1.5-m OSN
  22. GRB 090404: Swift-XRT Team refined analysis
  23. GRB 090404: Xinglong TNT optical Upper Limit
  24. GRB 090404: Swift-BAT refined analysis
  25. GRB 090404: Enhanced Swift-XRT position
  26. Fermi Gamma-ray Burst Monitor trigger 260428446 is not a GRB
  27. GRB 090404: Swift detection of a burst
  28. GRB 090401A: Suzaku WAM observation of the prompt emission
  29. GRB 090401B: Suzaku WAM observation of the prompt emission
  30. Konus-Wind observation of GRB 090401B
  31. GRB 090401B: Xinglong TNT optical Upper Limit
  32. GRB 090401B: VLA radio upper limit
  33. GRB 090401B: Upper limits of MITSuME optical observation
  34. GRB 090401B: NOT optical observations
  35. GRB 090328: Fermi-LAT refined analysis
  36. GRB 090401B: AGILE refined analysis
  37. GRB 090401B: Swift XRT Refined Analysis
  38. GRB 090331: Fermi GBM detection
  39. Konus-Wind observation of GRB 090401A
  40. GRB 090401B: Enhanced Swift-XRT position
  41. AGILE Gamma-ray detection of GRB 090401B
  42. GRB 090401B: Swift-BAT refined analysis
  43. GRB 090401B: Swift detection of a burst
  44. GRB 090328B: MASTER-Irkutsk prompt optical short burst observations
  45. GRB 090401, Swift-BAT refined analysis
  46. GRB 090323: Further TLS detections - a break?
  47. GRB 090401: Swift detection of a burst
  48. GRB 090324: Suzaku WAM observation of the prompt emission
  49. GRB 090328: Radio afterglow detection
  50. GRB 090326: Fermi GBM detection
  51. GRB 090328: BOOTES-3 optical observations
  52. GRB 090328: Fermi GBM Spectral Analysis
  53. GRB 090328B: Fermi GBM Detection
  54. GRB 090330: Fermi GBM detection
  55. GRB 090328: GROND Detection of the Optical/NIR Afterglow
  56. GRB 090328: Gemini South Redshift
  57. GRB 090328: Swift XRT refined analysis
  58. GRB090323: Optical observations from NOT
  59. Konus-Wind observation of GRB 090328
  60. GRB 090328: IPN Triangulation
  61. GRB 090328: Swift UVOT observations
  62. GRB 090323: WSRT Radio Detection
  63. GRB 090328: Updated position/optical afterglow candidate
  64. GRB 090328: Possible Swift/XRT detection
  65. Fermi LAT and GBM detections of GRB090328
  66. GRB 090323: Radio afterglow detection
  67. GRB 090323: Additional Lick observations
  68. GRB 090323: TLS detection at 5 days, no break
  69. GRB 090327: Fermi GBM detection
  70. GRB 090323: Faulkes Telescope South Observations
  71. GRB 090320B: MASTER-Net prompt optical observations
  72. GRB 090323: RTT150 optical observations
  73. GRB 090323: Lick observations
  74. GRB 090323: Fermi GBM Spectral Analysis
  75. GRB 090323: Optical observation of xinglong TNT
  76. GRB 090323 TLS detection - still bright
  77. GRB 090323: UVOT Detection of Afterglow
  78. GRB 090323: Swift-XRT refined analysis
  79. Konus-Wind observation of GRB 090323
  80. GRB 090324: SuperAGILE Localization of a Long GRB
  81. GRB 090323 Gemini-South Redshift
  82. GRB 090323: P60 Afterglow Confirmation
  83. GRB 090323: GROND Detection of the Afterglow and Photo-z
  84. SGR J1550-5418: two Fermi GBM triggers on March 22
  85. GRB 090323: Possible XRT Counterpart
  86. IPN triangulation of GRB090323
  87. GRB 090320C: Fermi GBM Detection
  88. Fermi GBM and LAT detections of GRB 090323
  89. GRB 090320B: Fermi GBM detection.
  90. GRB 090319: Fermi GBM detection
  91. GRB 090320A: Fermi GBM detection
  92. GRB 090313: WSRT Radio Detection
  93. X-shooter observations of GRB 090313
  94. GRB 090315: Suzaku WAM observation of the prompt emission
  95. GRB 090313: VLT spectroscopy
  96. GRB090313: radio detection with the VLA
  97. Konus-Wind observation of GRB 090315
  98. IPN Triangulation of GRB090315 and Tupi Detection of Muon Increase
  99. GRB 090313, SMARTS optical/IR observations
  100. Further radio observation of GRB 090313

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