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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 090418: Swift-BAT refined analysis
  2. GRB 090417B: Galaxy redshift
  3. GRB 090417B: Swift-XRT refined analysis
  4. GRB 090418: Enhanced Swift-XRT position
  5. GRB 090417B: Swift-BAT further refined analysis
  6. GRB 090418: PAIRITEL NIR detection
  7. GRB 090418 Lick Redshift
  8. GRB 090418: ROTSE-III Confirmation of Optical Counterpart
  9. GRB 090418: Swift detection of a burst with optical afterglow
  10. GRB 090418 OA candidate
  11. GRB 090411B: Suzaku WAM observation of the prompt emission
  12. GRB 090411A: Suzaku WAM observation of the prompt emission
  13. GRB 090417B: Subaru NIR Observations
  14. GRB 090417B: Liverpool Telescope observations
  15. GRB 090417B: MITSuME Okayama optical upper limits
  16. GRB090417B: Xinglong TNT optical upper limit
  17. GRB 090417B: optical observations
  18. GRB090417B: optical observations
  19. GRB 090417B: Swift-BAT refined analysis
  20. GRB 090417A: Swift-BAT refined analysis
  21. GRB 090417A: Early-type nature of the putative host
  22. GRB 090417A: nearby galaxy redshift
  23. GRB 090417B: Swift detection of a burst
  24. GRB 090417: 2MASS galaxy within BAT Localization
  25. GRB 090417: Swift detection of a short burst
  26. GRB 090412: Fermi GBM detection
  27. GRB 090411B: Fermi GBM detection
  28. GRB 090411A: Fermi GBM detection
  29. GRB 090410: Suzaku WAM observation of the prompt emission
  30. GRB 090410: GROND upper limits
  31. Fermi GBM trigger 261106787 is not a GRB
  32. GRB 090410: MITSuME optical upper limits
  33. GRB 090408b: IPN Triangulation
  34. GRB 090328b: IPN Triangulation
  35. GRB 090410: Swift-BAT refined analysis
  36. GRB 090410: Swift detection of a burst
  37. Konus-Wind and Konus-RF observations of GRB 090408b
  38. GRB090408 : TAOS optical observations
  39. GRB 090409: Fermi GBM detection
  40. Swift-BAT Trigger 348781 is not a GRB
  41. Swift-BAT Trigger 348720 is not a GRB
  42. GRB 090406: pseudo-z= 0.91 from prompt emission spectrum
  43. GRB090408, RIMOTS optical upper limits
  44. GRB 090408: Xinglong TNT optical Upper Limit
  45. Swift-BAT trigger 348781: almost certainly not a burst
  46. Fermi GBM Detection of a weak source
  47. GRB 090408B: MASTER II-Kourovka optical observations
  48. GRB 090408: Swift detection of a burst
  49. GRB 090407: GROND upper limits
  50. GRB 090407: VLT observations
  51. GRB 090407: Swift-XRT refined analysis
  52. GRB 090407: Swift UVOT Upper Limits
  53. GRB 090407: Enhanced Swift-XRT position
  54. GRB 090407: Swift-BAT refined analysis
  55. Konus-Wind and Konus-RF observations of GRB 090406
  56. GRB 090407: ROTSE-III Optical Limits
  57. GRB 090407: Swift detection of a burst
  58. GRB 090404: millimeter detection
  59. GRB 090404: nIR observations at Calar Alto
  60. GRB 090405: Fermi GBM Detection
  61. GRB 090403: Fermi GBM detection
  62. GRB 090404: GROND upper limits
  63. GRB 090404: further NOT observations
  64. Swift/UVOT observations of GRB090404
  65. GRB 090404: NOT observations
  66. GRB 090404: optical observations at BOOTES-3 and 1.5-m OSN
  67. GRB 090404: Swift-XRT Team refined analysis
  68. GRB 090404: Xinglong TNT optical Upper Limit
  69. GRB 090404: Swift-BAT refined analysis
  70. GRB 090404: Enhanced Swift-XRT position
  71. Fermi Gamma-ray Burst Monitor trigger 260428446 is not a GRB
  72. GRB 090404: Swift detection of a burst
  73. GRB 090401A: Suzaku WAM observation of the prompt emission
  74. GRB 090401B: Suzaku WAM observation of the prompt emission
  75. Konus-Wind observation of GRB 090401B
  76. GRB 090401B: Xinglong TNT optical Upper Limit
  77. GRB 090401B: VLA radio upper limit
  78. GRB 090401B: Upper limits of MITSuME optical observation
  79. GRB090401B, RIMOTS optical upper limits
  80. GRB 090401B: NOT optical observations
  81. GRB 090328: Fermi-LAT refined analysis
  82. Swift/UVOT observations of GRB090401B
  83. GRB 090401B: AGILE refined analysis
  84. Swift/UVOT observations of GRB090401B
  85. GRB 090401B: Swift XRT Refined Analysis
  86. GRB 090331: Fermi GBM detection
  87. Konus-Wind observation of GRB 090401A
  88. GRB 090401B: Enhanced Swift-XRT position
  89. AGILE Gamma-ray detection of GRB 090401B
  90. GRB 090401B: Swift-BAT refined analysis
  91. Swift/UVOT detection of GRB090401B
  92. GRB 090401B: Swift detection of a burst
  93. GRB 090328B: MASTER-Irkutsk prompt optical short burst observations
  94. GRB 090401, Swift-BAT refined analysis
  95. GRB 090323: Further TLS detections - a break?
  96. GRB 090401: Swift detection of a burst
  97. GRB 090324: Suzaku WAM observation of the prompt emission
  98. GRB 090328: Radio afterglow detection
  99. GRB 090326: Fermi GBM detection
  100. GRB 090328: BOOTES-3 optical observations

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