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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. GRB081203B: optical observations
  2. GRB 081210: Enhanced Swift-XRT position
  3. GRB 081210: Swift-BAT refined analysis
  4. GRB 081210: Swift detection of a burst with optical afterglow
  5. Konus-Wind observation of GRB 081209
  6. IPN triangulation of short hard GRB 081209
  7. GRB 081203A: optical observations
  8. GRB 081206C: Fermi GBM detection
  9. Radio observation of GRB 081121 with ATCA
  10. Radio observation of GRB 081118 with ATCA
  11. GRB 081206B: Fermi GBM detection
  12. GRB 081206: Fermi GBM detection
  13. GRB 081128: afterglow observations
  14. GRB 081203B: Suzaku WAM observation of the prompt emission
  15. GRB 081203B: Additional Gemini imaging
  16. Radio observation of GRB 081109 with ATCA
  17. Radio observation of GRB 081104 with ATCA
  18. Radio observation of GRB 081029 with ATCA
  19. Radio observation of GRB 081008 with ATCA
  20. GRB081203A: Ashra-1 observation of early optical and VHE-neutrino emission
  21. GRB 081203B: Gemini observations
  22. GRB 081128: optical observation in CrAO
  23. GRB081203A: Optical observations at Ishigaki
  24. GRB 081128: Optical afterglow observations
  25. GRB 081204: GROND Observations
  26. GRB081203B: optical observations
  27. Radio detection of GRB 081203B with the VLA
  28. GRB 081204: Magellan observations
  29. GRB081203A: Radio upper limit at 15 GHz
  30. GRB 081204B: Fermi GBM detection
  31. GRB 081204: Swift/UVOT Upper Limits
  32. GRB 081204: Swift XRT afterglow confirmation
  33. GRB081203A: MITSuME optical observation
  34. GRB 081203A: Optical observations of Xinglong TNT telescope
  35. GRB 081203A: Skynet/GORT Detections
  36. GRB 081204: Swift XRT afterglow candidate
  37. GRB081203A: optical observation
  38. GRB 081204 : a long GRB localized by INTEGRAL
  39. VLA Radio upper limit on GRB 081203A
  40. Swift-XRT observations of GRB 081203B
  41. Konus-Wind observation of GRB 081203A
  42. Konus-Wind observation of GRB 081203B
  43. GRB081203A: Swift-XRT refined analysis
  44. GRB 081203B: optical observations
  45. GRB 081203B: SDSS upper limits at the position of the optical afterglow
  46. Swift/UVOT detection of GRB081203B
  47. GRB 081203B: Swift-XRT candidate afterglow.
  48. GRB 081203A: optical observations
  49. Swift UVOT observations of GRB 081203A
  50. GRB 081203B: Naming correction for burst detected in Swift-BAT slew data
  51. GRB081203A: Swift/UVOT grism redshift
  52. GRB 081203A: Burst detection from Swift-BAT slew data
  53. GRB 081203A: Swift-BAT refined analysis
  54. GRB 081203: Enhanced Swift-XRT position
  55. GRB 081130B: MASTER prompt optical observations
  56. GRB081203: optical observation
  57. GRB 081203: Swift detection of a burst with a bright optical counterpart
  58. GRB 081128: optical observation
  59. GRB 081130B: Fermi GBM detection
  60. GRB 081130: Fermi GBM detection
  61. Swift Trigger 335971: Swift/UVOT Observations
  62. GRB 081126: afterglow photometry
  63. GRB 081126: Fermi GBM detection
  64. Fermi Gamma-ray Burst Monitor trigger 249166723 reclassification
  65. VLA Radio upper limit on GRB 081126
  66. GRB 081129: Fermi GBM detection
  67. GRB 081130: MASTER VWF prompt optical observations Fermi GRB
  68. GRB 081128A: optical observations
  69. Swift Trigger 335971 is probably not a real source
  70. Trigger 335971: Swift possible detection of a burst
  71. GRB081128: Swift/UVOT Upper Limits
  72. SGR 1806-20: Fermi GBM detection.
  73. GRB 081122B: Fermi GBM Detection
  74. GRB 081128: Swift-XRT refined analysis
  75. GRB 081128: Liverpool Telescope afterglow confirmation
  76. GRB081128: optical observations
  77. GRB081128 : Lulin optical follow-ups
  78. GRB 081128: Swift-BAT refined analysis
  79. GRB 081128: Enhanced Swift-XRT position
  80. GRB 081128: Optical observation of xinglong TNT
  81. GRB 081128: Swift detection of a burst
  82. GRB 081126: Swift observations continuing
  83. GRB081126: Afterglow photometry from Crni Vrh
  84. GRB 081126: GRT Optical Observation
  85. GRB 081127: Swift/UVOT Upper Limits
  86. GRB 081127: Swift-XRT refined analysis
  87. GRB 081127: Enhanced Swift-XRT position
  88. GRB 081126: Confirmation of the Optical Afterglow
  89. GRB 081127: Swift-BAT refined analysis
  90. Konus-Wind observation of GRB 081126
  91. GRB 081126: Swift-XRT refined analysis
  92. GRB 081127: Swift detection of a burst
  93. GRB 081126: Swift/UVOT Observations
  94. GRB 081126: optical observations
  95. GRB 081126: Swift-BAT refined analysis
  96. GRB 081126: Enhanced Swift-XRT position
  97. GRB 081126: TAROT Calern observatory optical observations
  98. GRB 081126: Swift detection of a burst
  99. GRB 081125: Fermi GBM detection
  100. GRB 081124: Fermi GBM detection

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