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

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