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

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