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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 081127: Enhanced Swift-XRT position
  2. GRB 081126: Confirmation of the Optical Afterglow
  3. GRB 081127: Swift-BAT refined analysis
  4. Konus-Wind observation of GRB 081126
  5. GRB 081126: Swift-XRT refined analysis
  6. GRB 081127: Swift detection of a burst
  7. GRB 081126: Swift/UVOT Observations
  8. GRB 081126: optical observations
  9. GRB 081126: Swift-BAT refined analysis
  10. GRB 081126: Enhanced Swift-XRT position
  11. GRB 081126: TAROT Calern observatory optical observations
  12. GRB 081126: Swift detection of a burst
  13. GRB 081125: Fermi GBM detection
  14. GRB 081124: Fermi GBM detection
  15. GRB 081120: Fermi GBM detection
  16. GRB 081118: Fermi GBM detection.
  17. GRB 081122: Fermi GBM detection
  18. Konus-Wind observation of GRB 081121
  19. GRB 081121, SMARTS optical/IR afterglow observations
  20. GRB081121: Fermi GBM detection
  21. Fermi GBM detection of a weak source
  22. GRB081121: Refined Swift/UVOT observations
  23. GRB 081121: Swift-XRT refined analysis
  24. GRB 081121: Magellan Redshift
  25. GRB 081121: Enhanced Swift-XRT position
  26. GRB 081121: GROND observations
  27. GRB 081121: Swift-BAT refined analysis
  28. GRB081121: Swift/UVOT observations
  29. GRB 081121: Swift detection of a burst
  30. GRB 081121: ROTSE-III Detection of Optical Counterpart
  31. GRB081118 : optical upper limit
  32. GRB 081016b, SMARTS optical/IR observations
  33. GRB 081119: Fermi GBM detection
  34. VLA Radio upper limit on GRB 081118
  35. GRB 081118: VLT redshift
  36. GRB 081118: Swift-XRT refined analysis
  37. GRB 081118: GROND detection of afterglow
  38. GRB 081118: optical afterglow candidate
  39. GRB 081118: Swift UVOT Upper Limits
  40. GRB 081118: Swift-BAT refined analysis
  41. GRB 081118: Enhanced Swift-XRT position
  42. GRB 081118: Swift detection of a burst
  43. GRB 081109A: confirmation of possible detection host galaxy
  44. Further Swift-XRT observations of the probable GRB 081105.
  45. GRB 081113: Fermi GBM detection
  46. GRB 081102: RTT150 Optical observations
  47. GRB 081110: Fermi GBM detection
  48. GRB 081110: MASTER: first optical observations Fermi GRB
  49. GRB 081109: TAROT La Silla observatory optical observations
  50. GRB 081102: MASTER refind and final results
  51. GRB 081109: GROND redshift limit and host extinction
  52. GRB 081025: Swift-XRT further analysis
  53. GRB 081024B: Swift-XRT late-time observations
  54. Swift-BAT refined analysis of trigger 334129
  55. GRB 081109B: Swift/UVOT refined analysis
  56. GRB 081109: GROND Detection of the Optical/NIR Afterglow Candidate
  57. GRB 081109A: Possible Swift-UVOT detection
  58. GRB 081109A: Faulkes Telescope South observations
  59. GRB 081109A, Swift-BAT refined analysis
  60. GRB 081109A: Swift-XRT refined analysis
  61. GRB 081109: Fermi GBM detection
  62. GRB 081109: Swift/UVOT upper limits
  63. GRB 081109A optical upper limit
  64. Swift-BAT Trigger 334129: possible burst
  65. GRB 081109: REM NIR afterglow detection
  66. GRB 081109: Swift detection of a burst
  67. GRB 081028 - PAIRITEL NIR detection
  68. GRB 081024C: Fermi Gamma-ray Burst Monitor detection
  69. SGR 1806-20: Fermi GBM detection
  70. GRB 081102B: Fermi GBM detection
  71. GRB 081105B: Fermi GBM detection
  72. GRB 081107: Fermi GBM detection
  73. GRB 081104: GROND found no Optical/NIR Afterglow
  74. GRB 081105: GROND Upper Limits
  75. Radio observation of GRB 080523 with ATCA
  76. Radio observation of GRB 080520 with ATCA
  77. GRB 081105: Observations from OSN
  78. UVOT/Swift observations of GRB081105
  79. Swift-XRT observations of GRB 081105
  80. GRB 081101B: Fermi GBM detection
  81. Radio observation of GRB 080516 with ATCA
  82. GRB 081105 Swift/BAT and IPN Localization
  83. GRB 081025: Fermi GBM observation
  84. GRB 081104: GROND Detection of the Optical/NIR Afterglow Candidate?
  85. GRB 081104: refined XRT analysis
  86. GRB 081104: Enhanced Swift-XRT position
  87. GRB 081104: Swift-BAT refined analysis
  88. GRB081104: Swift/UVOT Upper Limits
  89. Fermi-GBM detection of a Solar Flare
  90. Fermi Detection of GRB 081102
  91. GRB 081104 : Faulkes Telescope South observations
  92. GRB 081104: Swift-XRT position
  93. GRB 081104: Swift detection of a burst
  94. Radio observation of GRB 080130 with ATCA
  95. GRB 081102: MASTER prompt optical limit
  96. GRB 081102: Swift-XRT refined analysis
  97. GRB 081102: Swift/UVOT refined analysis
  98. GRB 081102: Swift-BAT refined analysis
  99. GRB 081102: Enhanced Swift-XRT position
  100. Radio observation of GRB 080218b with ATCA

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