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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 090418A: optical observations
  2. GRB 090418B: GROND observations
  3. GRB 090419: Swift/UVOT Observations
  4. GRB 090418B: Faulkes Telescope North observations
  5. GRB 090418A: Swift/UVOT Observations
  6. GRB 090417B: Swift/UVOT Upper Limits
  7. GRB 090417B Correction to the BAT refined analysis position
  8. GRB 090419: Swift-XRT refined analysis
  9. Konus-Wind observation of GRB 090418B
  10. GRB 090418: Erratum in GCN 9168
  11. GRB 090419: GROND detection of afterglow candidate
  12. GRB 090418: Optical observations with MITSuME Okayama and Ishigaki 1m telescope
  13. GRB 090419: Swift-BAT refined analysis
  14. VLA radio detection of GRB 090418
  15. VLA radio upper limit on GRB 090417B
  16. GRB 090419: Enhanced Swift-XRT position
  17. GRB 090418: Swift XRT refined analysis
  18. GRB 090418A: ROTSE-III Refined Analysis
  19. GRB 090419: Swift detection of a burst
  20. VLA observations of short burst GRB 090417A
  21. GRB 090418B: Detection of a bright burst from Swift-BAT slew data
  22. GRB 090417B: Gemini imaging
  23. GRB 090418: Swift-BAT refined analysis
  24. GRB 090417B: Galaxy redshift
  25. GRB 090417B: Swift-XRT refined analysis
  26. GRB 090418: Enhanced Swift-XRT position
  27. GRB 090417B: Swift-BAT further refined analysis
  28. GRB 090418: PAIRITEL NIR detection
  29. GRB 090418 Lick Redshift
  30. GRB 090418: ROTSE-III Confirmation of Optical Counterpart
  31. GRB 090418: Swift detection of a burst with optical afterglow
  32. GRB 090418 OA candidate
  33. GRB 090411B: Suzaku WAM observation of the prompt emission
  34. GRB 090411A: Suzaku WAM observation of the prompt emission
  35. GRB 090417B: Subaru NIR Observations
  36. GRB 090417B: Liverpool Telescope observations
  37. GRB 090417B: MITSuME Okayama optical upper limits
  38. GRB090417B: Xinglong TNT optical upper limit
  39. GRB 090417B: optical observations
  40. GRB090417B: optical observations
  41. GRB 090417B: Swift-BAT refined analysis
  42. GRB 090417A: Swift-BAT refined analysis
  43. GRB 090417A: Early-type nature of the putative host
  44. GRB 090417A: nearby galaxy redshift
  45. GRB 090417B: Swift detection of a burst
  46. GRB 090417: 2MASS galaxy within BAT Localization
  47. GRB 090417: Swift detection of a short burst
  48. GRB 090412: Fermi GBM detection
  49. GRB 090411B: Fermi GBM detection
  50. GRB 090411A: Fermi GBM detection
  51. GRB 090410: Suzaku WAM observation of the prompt emission
  52. GRB 090410: GROND upper limits
  53. Fermi GBM trigger 261106787 is not a GRB
  54. GRB 090410: MITSuME optical upper limits
  55. GRB 090408b: IPN Triangulation
  56. GRB 090328b: IPN Triangulation
  57. GRB 090410: Swift-BAT refined analysis
  58. GRB 090410: Swift detection of a burst
  59. Konus-Wind and Konus-RF observations of GRB 090408b
  60. GRB090408 : TAOS optical observations
  61. GRB 090409: Fermi GBM detection
  62. Swift-BAT Trigger 348781 is not a GRB
  63. Swift-BAT Trigger 348720 is not a GRB
  64. GRB 090406: pseudo-z= 0.91 from prompt emission spectrum
  65. GRB090408, RIMOTS optical upper limits
  66. GRB 090408: Xinglong TNT optical Upper Limit
  67. Swift-BAT trigger 348781: almost certainly not a burst
  68. Fermi GBM Detection of a weak source
  69. GRB 090408B: MASTER II-Kourovka optical observations
  70. GRB 090408: Swift detection of a burst
  71. GRB 090407: GROND upper limits
  72. GRB 090407: VLT observations
  73. GRB 090407: Swift-XRT refined analysis
  74. GRB 090407: Swift UVOT Upper Limits
  75. GRB 090407: Enhanced Swift-XRT position
  76. GRB 090407: Swift-BAT refined analysis
  77. Konus-Wind and Konus-RF observations of GRB 090406
  78. GRB 090407: ROTSE-III Optical Limits
  79. GRB 090407: Swift detection of a burst
  80. GRB 090404: millimeter detection
  81. GRB 090404: nIR observations at Calar Alto
  82. GRB 090405: Fermi GBM Detection
  83. GRB 090403: Fermi GBM detection
  84. GRB 090404: GROND upper limits
  85. GRB 090404: further NOT observations
  86. Swift/UVOT observations of GRB090404
  87. GRB 090404: NOT observations
  88. GRB 090404: optical observations at BOOTES-3 and 1.5-m OSN
  89. GRB 090404: Swift-XRT Team refined analysis
  90. GRB 090404: Xinglong TNT optical Upper Limit
  91. GRB 090404: Swift-BAT refined analysis
  92. GRB 090404: Enhanced Swift-XRT position
  93. Fermi Gamma-ray Burst Monitor trigger 260428446 is not a GRB
  94. GRB 090404: Swift detection of a burst
  95. GRB 090401A: Suzaku WAM observation of the prompt emission
  96. GRB 090401B: Suzaku WAM observation of the prompt emission
  97. Konus-Wind observation of GRB 090401B
  98. GRB 090401B: Xinglong TNT optical Upper Limit
  99. GRB 090401B: VLA radio upper limit
  100. GRB 090401B: Upper limits of MITSuME optical observation

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