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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 081128: Swift detection of a burst
  2. GRB 081126: Swift observations continuing
  3. GRB081126: Afterglow photometry from Crni Vrh
  4. GRB 081126: GRT Optical Observation
  5. GRB 081127: Swift/UVOT Upper Limits
  6. GRB 081127: Swift-XRT refined analysis
  7. GRB 081127: Enhanced Swift-XRT position
  8. GRB 081126: Confirmation of the Optical Afterglow
  9. GRB 081127: Swift-BAT refined analysis
  10. Konus-Wind observation of GRB 081126
  11. GRB 081126: Swift-XRT refined analysis
  12. GRB 081127: Swift detection of a burst
  13. GRB 081126: Swift/UVOT Observations
  14. GRB 081126: optical observations
  15. GRB 081126: Swift-BAT refined analysis
  16. GRB 081126: Enhanced Swift-XRT position
  17. GRB 081126: TAROT Calern observatory optical observations
  18. GRB 081126: Swift detection of a burst
  19. GRB 081125: Fermi GBM detection
  20. GRB 081124: Fermi GBM detection
  21. GRB 081120: Fermi GBM detection
  22. GRB 081118: Fermi GBM detection.
  23. GRB 081122: Fermi GBM detection
  24. Konus-Wind observation of GRB 081121
  25. GRB 081121, SMARTS optical/IR afterglow observations
  26. GRB081121: Fermi GBM detection
  27. Fermi GBM detection of a weak source
  28. GRB081121: Refined Swift/UVOT observations
  29. GRB 081121: Swift-XRT refined analysis
  30. GRB 081121: Magellan Redshift
  31. GRB 081121: Enhanced Swift-XRT position
  32. GRB 081121: GROND observations
  33. GRB 081121: Swift-BAT refined analysis
  34. GRB081121: Swift/UVOT observations
  35. GRB 081121: Swift detection of a burst
  36. GRB 081121: ROTSE-III Detection of Optical Counterpart
  37. GRB081118 : optical upper limit
  38. GRB 081016b, SMARTS optical/IR observations
  39. GRB 081119: Fermi GBM detection
  40. VLA Radio upper limit on GRB 081118
  41. GRB 081118: VLT redshift
  42. GRB 081118: Swift-XRT refined analysis
  43. GRB 081118: GROND detection of afterglow
  44. GRB 081118: optical afterglow candidate
  45. GRB 081118: Swift UVOT Upper Limits
  46. GRB 081118: Swift-BAT refined analysis
  47. GRB 081118: Enhanced Swift-XRT position
  48. GRB 081118: Swift detection of a burst
  49. GRB 081109A: confirmation of possible detection host galaxy
  50. Further Swift-XRT observations of the probable GRB 081105.
  51. GRB 081113: Fermi GBM detection
  52. GRB 081102: RTT150 Optical observations
  53. GRB 081110: Fermi GBM detection
  54. GRB 081110: MASTER: first optical observations Fermi GRB
  55. GRB 081109: TAROT La Silla observatory optical observations
  56. GRB 081102: MASTER refind and final results
  57. GRB 081109: GROND redshift limit and host extinction
  58. GRB 081025: Swift-XRT further analysis
  59. GRB 081024B: Swift-XRT late-time observations
  60. Swift-BAT refined analysis of trigger 334129
  61. GRB 081109B: Swift/UVOT refined analysis
  62. GRB 081109: GROND Detection of the Optical/NIR Afterglow Candidate
  63. GRB 081109A: Possible Swift-UVOT detection
  64. GRB 081109A: Faulkes Telescope South observations
  65. GRB 081109A, Swift-BAT refined analysis
  66. GRB 081109A: Swift-XRT refined analysis
  67. GRB 081109: Fermi GBM detection
  68. GRB 081109: Swift/UVOT upper limits
  69. GRB 081109A optical upper limit
  70. Swift-BAT Trigger 334129: possible burst
  71. GRB 081109: REM NIR afterglow detection
  72. GRB 081109: Swift detection of a burst
  73. GRB 081028 - PAIRITEL NIR detection
  74. GRB 081024C: Fermi Gamma-ray Burst Monitor detection
  75. SGR 1806-20: Fermi GBM detection
  76. GRB 081102B: Fermi GBM detection
  77. GRB 081105B: Fermi GBM detection
  78. GRB 081107: Fermi GBM detection
  79. GRB 081104: GROND found no Optical/NIR Afterglow
  80. GRB 081105: GROND Upper Limits
  81. Radio observation of GRB 080523 with ATCA
  82. Radio observation of GRB 080520 with ATCA
  83. GRB 081105: Observations from OSN
  84. UVOT/Swift observations of GRB081105
  85. Swift-XRT observations of GRB 081105
  86. GRB 081101B: Fermi GBM detection
  87. Radio observation of GRB 080516 with ATCA
  88. GRB 081105 Swift/BAT and IPN Localization
  89. GRB 081025: Fermi GBM observation
  90. GRB 081104: GROND Detection of the Optical/NIR Afterglow Candidate?
  91. GRB 081104: refined XRT analysis
  92. GRB 081104: Enhanced Swift-XRT position
  93. GRB 081104: Swift-BAT refined analysis
  94. GRB081104: Swift/UVOT Upper Limits
  95. Fermi-GBM detection of a Solar Flare
  96. Fermi Detection of GRB 081102
  97. GRB 081104 : Faulkes Telescope South observations
  98. GRB 081104: Swift-XRT position
  99. GRB 081104: Swift detection of a burst
  100. Radio observation of GRB 080130 with ATCA

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