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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 081211: Enhanced Swift-XRT position
  2. GRB 081210: Swift/UVOT refined analysis
  3. GRB 081211: Swift detection of a burst
  4. GRB 081210: Swift-XRT refined analysis
  5. GRB081203B: optical observations
  6. GRB 081210: Enhanced Swift-XRT position
  7. GRB 081210: Swift-BAT refined analysis
  8. GRB 081210: Swift detection of a burst with optical afterglow
  9. Konus-Wind observation of GRB 081209
  10. IPN triangulation of short hard GRB 081209
  11. GRB 081203A: optical observations
  12. GRB 081206C: Fermi GBM detection
  13. Radio observation of GRB 081121 with ATCA
  14. Radio observation of GRB 081118 with ATCA
  15. GRB 081206B: Fermi GBM detection
  16. GRB 081206: Fermi GBM detection
  17. GRB 081128: afterglow observations
  18. GRB 081203B: Suzaku WAM observation of the prompt emission
  19. GRB 081203B: Additional Gemini imaging
  20. Radio observation of GRB 081109 with ATCA
  21. Radio observation of GRB 081104 with ATCA
  22. Radio observation of GRB 081029 with ATCA
  23. Radio observation of GRB 081008 with ATCA
  24. GRB081203A: Ashra-1 observation of early optical and VHE-neutrino emission
  25. GRB 081203B: Gemini observations
  26. GRB 081128: optical observation in CrAO
  27. GRB081203A: Optical observations at Ishigaki
  28. GRB 081128: Optical afterglow observations
  29. GRB 081204: GROND Observations
  30. GRB081203B: optical observations
  31. Radio detection of GRB 081203B with the VLA
  32. GRB 081204: Magellan observations
  33. GRB081203A: Radio upper limit at 15 GHz
  34. GRB 081204B: Fermi GBM detection
  35. GRB 081204: Swift/UVOT Upper Limits
  36. GRB 081204: Swift XRT afterglow confirmation
  37. GRB081203A: MITSuME optical observation
  38. GRB 081203A: Optical observations of Xinglong TNT telescope
  39. GRB 081203A: Skynet/GORT Detections
  40. GRB 081204: Swift XRT afterglow candidate
  41. GRB081203A: optical observation
  42. GRB 081204 : a long GRB localized by INTEGRAL
  43. VLA Radio upper limit on GRB 081203A
  44. Swift-XRT observations of GRB 081203B
  45. Konus-Wind observation of GRB 081203A
  46. Konus-Wind observation of GRB 081203B
  47. GRB081203A: Swift-XRT refined analysis
  48. GRB 081203B: optical observations
  49. GRB 081203B: SDSS upper limits at the position of the optical afterglow
  50. Swift/UVOT detection of GRB081203B
  51. GRB 081203B: Swift-XRT candidate afterglow.
  52. GRB 081203A: optical observations
  53. Swift UVOT observations of GRB 081203A
  54. GRB 081203B: Naming correction for burst detected in Swift-BAT slew data
  55. GRB081203A: Swift/UVOT grism redshift
  56. GRB 081203A: Burst detection from Swift-BAT slew data
  57. GRB 081203A: Swift-BAT refined analysis
  58. GRB 081203: Enhanced Swift-XRT position
  59. GRB 081130B: MASTER prompt optical observations
  60. GRB081203: optical observation
  61. GRB 081203: Swift detection of a burst with a bright optical counterpart
  62. GRB 081128: optical observation
  63. GRB 081130B: Fermi GBM detection
  64. GRB 081130: Fermi GBM detection
  65. Swift Trigger 335971: Swift/UVOT Observations
  66. GRB 081126: afterglow photometry
  67. GRB 081126: Fermi GBM detection
  68. Fermi Gamma-ray Burst Monitor trigger 249166723 reclassification
  69. VLA Radio upper limit on GRB 081126
  70. GRB 081129: Fermi GBM detection
  71. GRB 081130: MASTER VWF prompt optical observations Fermi GRB
  72. GRB 081128A: optical observations
  73. Swift Trigger 335971 is probably not a real source
  74. Trigger 335971: Swift possible detection of a burst
  75. GRB081128: Swift/UVOT Upper Limits
  76. SGR 1806-20: Fermi GBM detection.
  77. GRB 081122B: Fermi GBM Detection
  78. GRB 081128: Swift-XRT refined analysis
  79. GRB 081128: Liverpool Telescope afterglow confirmation
  80. GRB081128: optical observations
  81. GRB081128 : Lulin optical follow-ups
  82. GRB 081128: Swift-BAT refined analysis
  83. GRB 081128: Enhanced Swift-XRT position
  84. GRB 081128: Optical observation of xinglong TNT
  85. GRB 081128: Swift detection of a burst
  86. GRB 081126: Swift observations continuing
  87. GRB081126: Afterglow photometry from Crni Vrh
  88. GRB 081126: GRT Optical Observation
  89. GRB 081127: Swift/UVOT Upper Limits
  90. GRB 081127: Swift-XRT refined analysis
  91. GRB 081127: Enhanced Swift-XRT position
  92. GRB 081126: Confirmation of the Optical Afterglow
  93. GRB 081127: Swift-BAT refined analysis
  94. Konus-Wind observation of GRB 081126
  95. GRB 081126: Swift-XRT refined analysis
  96. GRB 081127: Swift detection of a burst
  97. GRB 081126: Swift/UVOT Observations
  98. GRB 081126: optical observations
  99. GRB 081126: Swift-BAT refined analysis
  100. GRB 081126: Enhanced Swift-XRT position

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