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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"
  1. GRB 090410: Swift detection of a burst
  2. Konus-Wind and Konus-RF observations of GRB 090408b
  3. GRB090408 : TAOS optical observations
  4. GRB 090409: Fermi GBM detection
  5. Swift-BAT Trigger 348781 is not a GRB
  6. Swift-BAT Trigger 348720 is not a GRB
  7. GRB 090406: pseudo-z= 0.91 from prompt emission spectrum
  8. GRB090408, RIMOTS optical upper limits
  9. GRB 090408: Xinglong TNT optical Upper Limit
  10. Swift-BAT trigger 348781: almost certainly not a burst
  11. Fermi GBM Detection of a weak source
  12. GRB 090408B: MASTER II-Kourovka optical observations
  13. GRB 090408: Swift detection of a burst
  14. GRB 090407: GROND upper limits
  15. GRB 090407: VLT observations
  16. GRB 090407: Swift-XRT refined analysis
  17. GRB 090407: Swift UVOT Upper Limits
  18. GRB 090407: Enhanced Swift-XRT position
  19. GRB 090407: Swift-BAT refined analysis
  20. Konus-Wind and Konus-RF observations of GRB 090406
  21. GRB 090407: ROTSE-III Optical Limits
  22. GRB 090407: Swift detection of a burst
  23. GRB 090404: millimeter detection
  24. GRB 090404: nIR observations at Calar Alto
  25. GRB 090405: Fermi GBM Detection
  26. GRB 090403: Fermi GBM detection
  27. GRB 090404: GROND upper limits
  28. GRB 090404: further NOT observations
  29. Swift/UVOT observations of GRB090404
  30. GRB 090404: NOT observations
  31. GRB 090404: optical observations at BOOTES-3 and 1.5-m OSN
  32. GRB 090404: Swift-XRT Team refined analysis
  33. GRB 090404: Xinglong TNT optical Upper Limit
  34. GRB 090404: Swift-BAT refined analysis
  35. GRB 090404: Enhanced Swift-XRT position
  36. Fermi Gamma-ray Burst Monitor trigger 260428446 is not a GRB
  37. GRB 090404: Swift detection of a burst
  38. GRB 090401A: Suzaku WAM observation of the prompt emission
  39. GRB 090401B: Suzaku WAM observation of the prompt emission
  40. Konus-Wind observation of GRB 090401B
  41. GRB 090401B: Xinglong TNT optical Upper Limit
  42. GRB 090401B: VLA radio upper limit
  43. GRB 090401B: Upper limits of MITSuME optical observation
  44. GRB090401B, RIMOTS optical upper limits
  45. GRB 090401B: NOT optical observations
  46. GRB 090328: Fermi-LAT refined analysis
  47. Swift/UVOT observations of GRB090401B
  48. GRB 090401B: AGILE refined analysis
  49. Swift/UVOT observations of GRB090401B
  50. GRB 090401B: Swift XRT Refined Analysis
  51. GRB 090331: Fermi GBM detection
  52. Konus-Wind observation of GRB 090401A
  53. GRB 090401B: Enhanced Swift-XRT position
  54. AGILE Gamma-ray detection of GRB 090401B
  55. GRB 090401B: Swift-BAT refined analysis
  56. Swift/UVOT detection of GRB090401B
  57. GRB 090401B: Swift detection of a burst
  58. GRB 090328B: MASTER-Irkutsk prompt optical short burst observations
  59. GRB 090401, Swift-BAT refined analysis
  60. GRB 090323: Further TLS detections - a break?
  61. GRB 090401: Swift detection of a burst
  62. GRB 090324: Suzaku WAM observation of the prompt emission
  63. GRB 090328: Radio afterglow detection
  64. GRB 090326: Fermi GBM detection
  65. GRB 090328: BOOTES-3 optical observations
  66. GRB 090328: Fermi GBM Spectral Analysis
  67. GRB 090328B: Fermi GBM Detection
  68. GRB 090330: Fermi GBM detection
  69. GRB 090328: GROND Detection of the Optical/NIR Afterglow
  70. GRB 090328: Gemini South Redshift
  71. GRB 090328: Swift XRT refined analysis
  72. GRB090323: Optical observations from NOT
  73. Konus-Wind observation of GRB 090328
  74. GRB 090328: IPN Triangulation
  75. GRB 090328: Swift UVOT observations
  76. GRB 090323: WSRT Radio Detection
  77. GRB 090328: Updated position/optical afterglow candidate
  78. GRB 090328: Possible Swift/XRT detection
  79. Fermi LAT and GBM detections of GRB090328
  80. GRB 090323: Radio afterglow detection
  81. GRB 090323: Additional Lick observations
  82. GRB 090323: TLS detection at 5 days, no break
  83. GRB 090327: Fermi GBM detection
  84. GRB 090323: Faulkes Telescope South Observations
  85. GRB 090320B: MASTER-Net prompt optical observations
  86. GRB 090323: RTT150 optical observations
  87. GRB 090323: Lick observations
  88. GRB 090323: Fermi GBM Spectral Analysis
  89. GRB 090323: Optical observation of xinglong TNT
  90. GRB 090323 TLS detection - still bright
  91. GRB 090323: UVOT Detection of Afterglow
  92. GRB 090323: Swift-XRT refined analysis
  93. Konus-Wind observation of GRB 090323
  94. GRB 090324: SuperAGILE Localization of a Long GRB
  95. GRB 090323 Gemini-South Redshift
  96. GRB 090323: P60 Afterglow Confirmation
  97. GRB 090323: GROND Detection of the Afterglow and Photo-z
  98. SGR J1550-5418: two Fermi GBM triggers on March 22
  99. GRB 090323: Possible XRT Counterpart
  100. IPN triangulation of GRB090323

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