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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. VLA Radio upper limit on GRB 081126
  2. GRB 081129: Fermi GBM detection
  3. GRB 081130: MASTER VWF prompt optical observations Fermi GRB
  4. GRB 081128A: optical observations
  5. Swift Trigger 335971 is probably not a real source
  6. Trigger 335971: Swift possible detection of a burst
  7. GRB081128: Swift/UVOT Upper Limits
  8. SGR 1806-20: Fermi GBM detection.
  9. GRB 081122B: Fermi GBM Detection
  10. GRB 081128: Swift-XRT refined analysis
  11. GRB 081128: Liverpool Telescope afterglow confirmation
  12. GRB081128: optical observations
  13. GRB081128 : Lulin optical follow-ups
  14. GRB 081128: Swift-BAT refined analysis
  15. GRB 081128: Enhanced Swift-XRT position
  16. GRB 081128: Optical observation of xinglong TNT
  17. GRB 081128: Swift detection of a burst
  18. GRB 081126: Swift observations continuing
  19. GRB081126: Afterglow photometry from Crni Vrh
  20. GRB 081126: GRT Optical Observation
  21. GRB 081127: Swift/UVOT Upper Limits
  22. GRB 081127: Swift-XRT refined analysis
  23. GRB 081127: Enhanced Swift-XRT position
  24. GRB 081126: Confirmation of the Optical Afterglow
  25. GRB 081127: Swift-BAT refined analysis
  26. Konus-Wind observation of GRB 081126
  27. GRB 081126: Swift-XRT refined analysis
  28. GRB 081127: Swift detection of a burst
  29. GRB 081126: Swift/UVOT Observations
  30. GRB 081126: optical observations
  31. GRB 081126: Swift-BAT refined analysis
  32. GRB 081126: Enhanced Swift-XRT position
  33. GRB 081126: TAROT Calern observatory optical observations
  34. GRB 081126: Swift detection of a burst
  35. GRB 081125: Fermi GBM detection
  36. GRB 081124: Fermi GBM detection
  37. GRB 081120: Fermi GBM detection
  38. GRB 081118: Fermi GBM detection.
  39. GRB 081122: Fermi GBM detection
  40. Konus-Wind observation of GRB 081121
  41. GRB 081121, SMARTS optical/IR afterglow observations
  42. GRB081121: Fermi GBM detection
  43. Fermi GBM detection of a weak source
  44. GRB081121: Refined Swift/UVOT observations
  45. GRB 081121: Swift-XRT refined analysis
  46. GRB 081121: Magellan Redshift
  47. GRB 081121: Enhanced Swift-XRT position
  48. GRB 081121: GROND observations
  49. GRB 081121: Swift-BAT refined analysis
  50. GRB081121: Swift/UVOT observations
  51. GRB 081121: Swift detection of a burst
  52. GRB 081121: ROTSE-III Detection of Optical Counterpart
  53. GRB081118 : optical upper limit
  54. GRB 081016b, SMARTS optical/IR observations
  55. GRB 081119: Fermi GBM detection
  56. VLA Radio upper limit on GRB 081118
  57. GRB 081118: VLT redshift
  58. GRB 081118: Swift-XRT refined analysis
  59. GRB 081118: GROND detection of afterglow
  60. GRB 081118: optical afterglow candidate
  61. GRB 081118: Swift UVOT Upper Limits
  62. GRB 081118: Swift-BAT refined analysis
  63. GRB 081118: Enhanced Swift-XRT position
  64. GRB 081118: Swift detection of a burst
  65. GRB 081109A: confirmation of possible detection host galaxy
  66. Further Swift-XRT observations of the probable GRB 081105.
  67. GRB 081113: Fermi GBM detection
  68. GRB 081102: RTT150 Optical observations
  69. GRB 081110: Fermi GBM detection
  70. GRB 081110: MASTER: first optical observations Fermi GRB
  71. GRB 081109: TAROT La Silla observatory optical observations
  72. GRB 081102: MASTER refind and final results
  73. GRB 081109: GROND redshift limit and host extinction
  74. GRB 081025: Swift-XRT further analysis
  75. GRB 081024B: Swift-XRT late-time observations
  76. Swift-BAT refined analysis of trigger 334129
  77. GRB 081109B: Swift/UVOT refined analysis
  78. GRB 081109: GROND Detection of the Optical/NIR Afterglow Candidate
  79. GRB 081109A: Possible Swift-UVOT detection
  80. GRB 081109A: Faulkes Telescope South observations
  81. GRB 081109A, Swift-BAT refined analysis
  82. GRB 081109A: Swift-XRT refined analysis
  83. GRB 081109: Fermi GBM detection
  84. GRB 081109: Swift/UVOT upper limits
  85. GRB 081109A optical upper limit
  86. Swift-BAT Trigger 334129: possible burst
  87. GRB 081109: REM NIR afterglow detection
  88. GRB 081109: Swift detection of a burst
  89. GRB 081028 - PAIRITEL NIR detection
  90. GRB 081024C: Fermi Gamma-ray Burst Monitor detection
  91. SGR 1806-20: Fermi GBM detection
  92. GRB 081102B: Fermi GBM detection
  93. GRB 081105B: Fermi GBM detection
  94. GRB 081107: Fermi GBM detection
  95. GRB 081104: GROND found no Optical/NIR Afterglow
  96. GRB 081105: GROND Upper Limits
  97. Radio observation of GRB 080523 with ATCA
  98. Radio observation of GRB 080520 with ATCA
  99. GRB 081105: Observations from OSN
  100. UVOT/Swift observations of GRB081105

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