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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 081203A: optical observations
  2. GRB 081206C: Fermi GBM detection
  3. Radio observation of GRB 081121 with ATCA
  4. Radio observation of GRB 081118 with ATCA
  5. GRB 081206B: Fermi GBM detection
  6. GRB 081206: Fermi GBM detection
  7. GRB 081128: afterglow observations
  8. GRB 081203B: Suzaku WAM observation of the prompt emission
  9. GRB 081203B: Additional Gemini imaging
  10. Radio observation of GRB 081109 with ATCA
  11. Radio observation of GRB 081104 with ATCA
  12. Radio observation of GRB 081029 with ATCA
  13. Radio observation of GRB 081008 with ATCA
  14. GRB081203A: Ashra-1 observation of early optical and VHE-neutrino emission
  15. GRB 081203B: Gemini observations
  16. GRB 081128: optical observation in CrAO
  17. GRB081203A: Optical observations at Ishigaki
  18. GRB 081128: Optical afterglow observations
  19. GRB 081204: GROND Observations
  20. GRB081203B: optical observations
  21. Radio detection of GRB 081203B with the VLA
  22. GRB 081204: Magellan observations
  23. GRB081203A: Radio upper limit at 15 GHz
  24. GRB 081204B: Fermi GBM detection
  25. GRB 081204: Swift/UVOT Upper Limits
  26. GRB 081204: Swift XRT afterglow confirmation
  27. GRB081203A: MITSuME optical observation
  28. GRB 081203A: Optical observations of Xinglong TNT telescope
  29. GRB 081203A: Skynet/GORT Detections
  30. GRB 081204: Swift XRT afterglow candidate
  31. GRB081203A: optical observation
  32. GRB 081204 : a long GRB localized by INTEGRAL
  33. VLA Radio upper limit on GRB 081203A
  34. Swift-XRT observations of GRB 081203B
  35. Konus-Wind observation of GRB 081203A
  36. Konus-Wind observation of GRB 081203B
  37. GRB081203A: Swift-XRT refined analysis
  38. GRB 081203B: optical observations
  39. GRB 081203B: SDSS upper limits at the position of the optical afterglow
  40. Swift/UVOT detection of GRB081203B
  41. GRB 081203B: Swift-XRT candidate afterglow.
  42. GRB 081203A: optical observations
  43. Swift UVOT observations of GRB 081203A
  44. GRB 081203B: Naming correction for burst detected in Swift-BAT slew data
  45. GRB081203A: Swift/UVOT grism redshift
  46. GRB 081203A: Burst detection from Swift-BAT slew data
  47. GRB 081203A: Swift-BAT refined analysis
  48. GRB 081203: Enhanced Swift-XRT position
  49. GRB 081130B: MASTER prompt optical observations
  50. GRB081203: optical observation
  51. GRB 081203: Swift detection of a burst with a bright optical counterpart
  52. GRB 081128: optical observation
  53. GRB 081130B: Fermi GBM detection
  54. GRB 081130: Fermi GBM detection
  55. Swift Trigger 335971: Swift/UVOT Observations
  56. GRB 081126: afterglow photometry
  57. GRB 081126: Fermi GBM detection
  58. Fermi Gamma-ray Burst Monitor trigger 249166723 reclassification
  59. VLA Radio upper limit on GRB 081126
  60. GRB 081129: Fermi GBM detection
  61. GRB 081130: MASTER VWF prompt optical observations Fermi GRB
  62. GRB 081128A: optical observations
  63. Swift Trigger 335971 is probably not a real source
  64. Trigger 335971: Swift possible detection of a burst
  65. GRB081128: Swift/UVOT Upper Limits
  66. SGR 1806-20: Fermi GBM detection.
  67. GRB 081122B: Fermi GBM Detection
  68. GRB 081128: Swift-XRT refined analysis
  69. GRB 081128: Liverpool Telescope afterglow confirmation
  70. GRB081128: optical observations
  71. GRB081128 : Lulin optical follow-ups
  72. GRB 081128: Swift-BAT refined analysis
  73. GRB 081128: Enhanced Swift-XRT position
  74. GRB 081128: Optical observation of xinglong TNT
  75. GRB 081128: Swift detection of a burst
  76. GRB 081126: Swift observations continuing
  77. GRB081126: Afterglow photometry from Crni Vrh
  78. GRB 081126: GRT Optical Observation
  79. GRB 081127: Swift/UVOT Upper Limits
  80. GRB 081127: Swift-XRT refined analysis
  81. GRB 081127: Enhanced Swift-XRT position
  82. GRB 081126: Confirmation of the Optical Afterglow
  83. GRB 081127: Swift-BAT refined analysis
  84. Konus-Wind observation of GRB 081126
  85. GRB 081126: Swift-XRT refined analysis
  86. GRB 081127: Swift detection of a burst
  87. GRB 081126: Swift/UVOT Observations
  88. GRB 081126: optical observations
  89. GRB 081126: Swift-BAT refined analysis
  90. GRB 081126: Enhanced Swift-XRT position
  91. GRB 081126: TAROT Calern observatory optical observations
  92. GRB 081126: Swift detection of a burst
  93. GRB 081125: Fermi GBM detection
  94. GRB 081124: Fermi GBM detection
  95. GRB 081120: Fermi GBM detection
  96. GRB 081118: Fermi GBM detection.
  97. GRB 081122: Fermi GBM detection
  98. Konus-Wind observation of GRB 081121
  99. GRB 081121, SMARTS optical/IR afterglow observations
  100. GRB081121: Fermi GBM detection

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