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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 090411B: Suzaku WAM observation of the prompt emission
  2. GRB 090411A: Suzaku WAM observation of the prompt emission
  3. GRB 090417B: Subaru NIR Observations
  4. GRB 090417B: Liverpool Telescope observations
  5. GRB 090417B: MITSuME Okayama optical upper limits
  6. GRB090417B: Xinglong TNT optical upper limit
  7. GRB 090417B: optical observations
  8. GRB090417B: optical observations
  9. GRB 090417B: Swift-BAT refined analysis
  10. GRB 090417A: Swift-BAT refined analysis
  11. GRB 090417A: Early-type nature of the putative host
  12. GRB 090417A: nearby galaxy redshift
  13. GRB 090417B: Swift detection of a burst
  14. GRB 090417: 2MASS galaxy within BAT Localization
  15. GRB 090417: Swift detection of a short burst
  16. GRB 090412: Fermi GBM detection
  17. GRB 090411B: Fermi GBM detection
  18. GRB 090411A: Fermi GBM detection
  19. GRB 090410: Suzaku WAM observation of the prompt emission
  20. GRB 090410: GROND upper limits
  21. Fermi GBM trigger 261106787 is not a GRB
  22. GRB 090410: MITSuME optical upper limits
  23. GRB 090408b: IPN Triangulation
  24. GRB 090328b: IPN Triangulation
  25. GRB 090410: Swift-BAT refined analysis
  26. GRB 090410: Swift detection of a burst
  27. Konus-Wind and Konus-RF observations of GRB 090408b
  28. GRB090408 : TAOS optical observations
  29. GRB 090409: Fermi GBM detection
  30. Swift-BAT Trigger 348781 is not a GRB
  31. Swift-BAT Trigger 348720 is not a GRB
  32. GRB 090406: pseudo-z= 0.91 from prompt emission spectrum
  33. GRB090408, RIMOTS optical upper limits
  34. GRB 090408: Xinglong TNT optical Upper Limit
  35. Swift-BAT trigger 348781: almost certainly not a burst
  36. Fermi GBM Detection of a weak source
  37. GRB 090408B: MASTER II-Kourovka optical observations
  38. GRB 090408: Swift detection of a burst
  39. GRB 090407: GROND upper limits
  40. GRB 090407: VLT observations
  41. GRB 090407: Swift-XRT refined analysis
  42. GRB 090407: Swift UVOT Upper Limits
  43. GRB 090407: Enhanced Swift-XRT position
  44. GRB 090407: Swift-BAT refined analysis
  45. Konus-Wind and Konus-RF observations of GRB 090406
  46. GRB 090407: ROTSE-III Optical Limits
  47. GRB 090407: Swift detection of a burst
  48. GRB 090404: millimeter detection
  49. GRB 090404: nIR observations at Calar Alto
  50. GRB 090405: Fermi GBM Detection
  51. GRB 090403: Fermi GBM detection
  52. GRB 090404: GROND upper limits
  53. GRB 090404: further NOT observations
  54. Swift/UVOT observations of GRB090404
  55. GRB 090404: NOT observations
  56. GRB 090404: optical observations at BOOTES-3 and 1.5-m OSN
  57. GRB 090404: Swift-XRT Team refined analysis
  58. GRB 090404: Xinglong TNT optical Upper Limit
  59. GRB 090404: Swift-BAT refined analysis
  60. GRB 090404: Enhanced Swift-XRT position
  61. Fermi Gamma-ray Burst Monitor trigger 260428446 is not a GRB
  62. GRB 090404: Swift detection of a burst
  63. GRB 090401A: Suzaku WAM observation of the prompt emission
  64. GRB 090401B: Suzaku WAM observation of the prompt emission
  65. Konus-Wind observation of GRB 090401B
  66. GRB 090401B: Xinglong TNT optical Upper Limit
  67. GRB 090401B: VLA radio upper limit
  68. GRB 090401B: Upper limits of MITSuME optical observation
  69. GRB090401B, RIMOTS optical upper limits
  70. GRB 090401B: NOT optical observations
  71. GRB 090328: Fermi-LAT refined analysis
  72. Swift/UVOT observations of GRB090401B
  73. GRB 090401B: AGILE refined analysis
  74. Swift/UVOT observations of GRB090401B
  75. GRB 090401B: Swift XRT Refined Analysis
  76. GRB 090331: Fermi GBM detection
  77. Konus-Wind observation of GRB 090401A
  78. GRB 090401B: Enhanced Swift-XRT position
  79. AGILE Gamma-ray detection of GRB 090401B
  80. GRB 090401B: Swift-BAT refined analysis
  81. Swift/UVOT detection of GRB090401B
  82. GRB 090401B: Swift detection of a burst
  83. GRB 090328B: MASTER-Irkutsk prompt optical short burst observations
  84. GRB 090401, Swift-BAT refined analysis
  85. GRB 090323: Further TLS detections - a break?
  86. GRB 090401: Swift detection of a burst
  87. GRB 090324: Suzaku WAM observation of the prompt emission
  88. GRB 090328: Radio afterglow detection
  89. GRB 090326: Fermi GBM detection
  90. GRB 090328: BOOTES-3 optical observations
  91. GRB 090328: Fermi GBM Spectral Analysis
  92. GRB 090328B: Fermi GBM Detection
  93. GRB 090330: Fermi GBM detection
  94. GRB 090328: GROND Detection of the Optical/NIR Afterglow
  95. GRB 090328: Gemini South Redshift
  96. GRB 090328: Swift XRT refined analysis
  97. GRB090323: Optical observations from NOT
  98. Konus-Wind observation of GRB 090328
  99. GRB 090328: IPN Triangulation
  100. GRB 090328: Swift UVOT observations

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