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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 090404: Enhanced Swift-XRT position
  2. Fermi Gamma-ray Burst Monitor trigger 260428446 is not a GRB
  3. GRB 090404: Swift detection of a burst
  4. GRB 090401A: Suzaku WAM observation of the prompt emission
  5. GRB 090401B: Suzaku WAM observation of the prompt emission
  6. Konus-Wind observation of GRB 090401B
  7. GRB 090401B: Xinglong TNT optical Upper Limit
  8. GRB 090401B: VLA radio upper limit
  9. GRB 090401B: Upper limits of MITSuME optical observation
  10. GRB090401B, RIMOTS optical upper limits
  11. GRB 090401B: NOT optical observations
  12. GRB 090328: Fermi-LAT refined analysis
  13. Swift/UVOT observations of GRB090401B
  14. GRB 090401B: AGILE refined analysis
  15. Swift/UVOT observations of GRB090401B
  16. GRB 090401B: Swift XRT Refined Analysis
  17. GRB 090331: Fermi GBM detection
  18. Konus-Wind observation of GRB 090401A
  19. GRB 090401B: Enhanced Swift-XRT position
  20. AGILE Gamma-ray detection of GRB 090401B
  21. GRB 090401B: Swift-BAT refined analysis
  22. Swift/UVOT detection of GRB090401B
  23. GRB 090401B: Swift detection of a burst
  24. GRB 090328B: MASTER-Irkutsk prompt optical short burst observations
  25. GRB 090401, Swift-BAT refined analysis
  26. GRB 090323: Further TLS detections - a break?
  27. GRB 090401: Swift detection of a burst
  28. GRB 090324: Suzaku WAM observation of the prompt emission
  29. GRB 090328: Radio afterglow detection
  30. GRB 090326: Fermi GBM detection
  31. GRB 090328: BOOTES-3 optical observations
  32. GRB 090328: Fermi GBM Spectral Analysis
  33. GRB 090328B: Fermi GBM Detection
  34. GRB 090330: Fermi GBM detection
  35. GRB 090328: GROND Detection of the Optical/NIR Afterglow
  36. GRB 090328: Gemini South Redshift
  37. GRB 090328: Swift XRT refined analysis
  38. GRB090323: Optical observations from NOT
  39. Konus-Wind observation of GRB 090328
  40. GRB 090328: IPN Triangulation
  41. GRB 090328: Swift UVOT observations
  42. GRB 090323: WSRT Radio Detection
  43. GRB 090328: Updated position/optical afterglow candidate
  44. GRB 090328: Possible Swift/XRT detection
  45. Fermi LAT and GBM detections of GRB090328
  46. GRB 090323: Radio afterglow detection
  47. GRB 090323: Additional Lick observations
  48. GRB 090323: TLS detection at 5 days, no break
  49. GRB 090327: Fermi GBM detection
  50. GRB 090323: Faulkes Telescope South Observations
  51. GRB 090320B: MASTER-Net prompt optical observations
  52. GRB 090323: RTT150 optical observations
  53. GRB 090323: Lick observations
  54. GRB 090323: Fermi GBM Spectral Analysis
  55. GRB 090323: Optical observation of xinglong TNT
  56. GRB 090323 TLS detection - still bright
  57. GRB 090323: UVOT Detection of Afterglow
  58. GRB 090323: Swift-XRT refined analysis
  59. Konus-Wind observation of GRB 090323
  60. GRB 090324: SuperAGILE Localization of a Long GRB
  61. GRB 090323 Gemini-South Redshift
  62. GRB 090323: P60 Afterglow Confirmation
  63. GRB 090323: GROND Detection of the Afterglow and Photo-z
  64. SGR J1550-5418: two Fermi GBM triggers on March 22
  65. GRB 090323: Possible XRT Counterpart
  66. IPN triangulation of GRB090323
  67. GRB 090320C: Fermi GBM Detection
  68. Fermi GBM and LAT detections of GRB 090323
  69. GRB 090320B: Fermi GBM detection.
  70. GRB 090319: Fermi GBM detection
  71. GRB 090320A: Fermi GBM detection
  72. Further 15GHz observations of GRB090313
  73. GRB 090313: WSRT Radio Detection
  74. X-shooter observations of GRB 090313
  75. A bright burst from AXP 1E 1547.0-5408/SGR J1550-5418
  76. GRB 090315: Suzaku WAM observation of the prompt emission
  77. GRB 090313: VLT spectroscopy
  78. GRB090313: radio detection with the VLA
  79. Konus-Wind observation of GRB 090315
  80. IPN Triangulation of GRB090315 and Tupi Detection of Muon Increase
  81. GRB 090313, SMARTS optical/IR observations
  82. Further radio observation of GRB 090313
  83. Further Swift/UVOT observations of GRB 090313
  84. GRB 090313: detection with CARMA in 3mm band
  85. GRB090305B: MASTER-net prompt optical short burst observations
  86. Radio detection of GRB090313
  87. GRB 090313: MITSuME Okayama observation
  88. GRB 090313: Additional Gemini-S photometry
  89. GRB 090313: WSRT Radio Observations
  90. GRB 090313: Light curve steepening
  91. GRB 090313: TAROT La Silla observatory optical detection
  92. GRB 090313: Gemini-S photometry
  93. GRB 090313: Zadko Telescope observations
  94. GRB 090313 - PAIRITEL NIR detections
  95. GRB 090313: Gemini-S redshift
  96. GRB 090313 optical observations
  97. GRB 090313: Ongoing plateau phase
  98. GRB 090313: Swift-XRT refined analysis
  99. GRB 090313: Swift/UVOT upper limits
  100. GRB 090313: Faulkes Telescope North observations

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