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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 081204: Swift/UVOT Upper Limits
  2. GRB 081204: Swift XRT afterglow confirmation
  3. GRB081203A: MITSuME optical observation
  4. GRB 081203A: Optical observations of Xinglong TNT telescope
  5. GRB 081203A: Skynet/GORT Detections
  6. GRB 081204: Swift XRT afterglow candidate
  7. GRB081203A: optical observation
  8. GRB 081204 : a long GRB localized by INTEGRAL
  9. VLA Radio upper limit on GRB 081203A
  10. Swift-XRT observations of GRB 081203B
  11. Konus-Wind observation of GRB 081203A
  12. Konus-Wind observation of GRB 081203B
  13. GRB081203A: Swift-XRT refined analysis
  14. GRB 081203B: optical observations
  15. GRB 081203B: SDSS upper limits at the position of the optical afterglow
  16. Swift/UVOT detection of GRB081203B
  17. GRB 081203B: Swift-XRT candidate afterglow.
  18. GRB 081203A: optical observations
  19. Swift UVOT observations of GRB 081203A
  20. GRB 081203B: Naming correction for burst detected in Swift-BAT slew data
  21. GRB081203A: Swift/UVOT grism redshift
  22. GRB 081203A: Burst detection from Swift-BAT slew data
  23. GRB 081203A: Swift-BAT refined analysis
  24. GRB 081203: Enhanced Swift-XRT position
  25. GRB 081130B: MASTER prompt optical observations
  26. GRB081203: optical observation
  27. GRB 081203: Swift detection of a burst with a bright optical counterpart
  28. GRB 081128: optical observation
  29. GRB 081130B: Fermi GBM detection
  30. GRB 081130: Fermi GBM detection
  31. Swift Trigger 335971: Swift/UVOT Observations
  32. GRB 081126: afterglow photometry
  33. GRB 081126: Fermi GBM detection
  34. Fermi Gamma-ray Burst Monitor trigger 249166723 reclassification
  35. VLA Radio upper limit on GRB 081126
  36. GRB 081129: Fermi GBM detection
  37. GRB 081130: MASTER VWF prompt optical observations Fermi GRB
  38. GRB 081128A: optical observations
  39. Swift Trigger 335971 is probably not a real source
  40. Trigger 335971: Swift possible detection of a burst
  41. GRB081128: Swift/UVOT Upper Limits
  42. SGR 1806-20: Fermi GBM detection.
  43. GRB 081122B: Fermi GBM Detection
  44. GRB 081128: Swift-XRT refined analysis
  45. GRB 081128: Liverpool Telescope afterglow confirmation
  46. GRB081128: optical observations
  47. GRB081128 : Lulin optical follow-ups
  48. GRB 081128: Swift-BAT refined analysis
  49. GRB 081128: Enhanced Swift-XRT position
  50. GRB 081128: Optical observation of xinglong TNT
  51. GRB 081128: Swift detection of a burst
  52. GRB 081126: Swift observations continuing
  53. GRB081126: Afterglow photometry from Crni Vrh
  54. GRB 081126: GRT Optical Observation
  55. GRB 081127: Swift/UVOT Upper Limits
  56. GRB 081127: Swift-XRT refined analysis
  57. GRB 081127: Enhanced Swift-XRT position
  58. GRB 081126: Confirmation of the Optical Afterglow
  59. GRB 081127: Swift-BAT refined analysis
  60. Konus-Wind observation of GRB 081126
  61. GRB 081126: Swift-XRT refined analysis
  62. GRB 081127: Swift detection of a burst
  63. GRB 081126: Swift/UVOT Observations
  64. GRB 081126: optical observations
  65. GRB 081126: Swift-BAT refined analysis
  66. GRB 081126: Enhanced Swift-XRT position
  67. GRB 081126: TAROT Calern observatory optical observations
  68. GRB 081126: Swift detection of a burst
  69. GRB 081125: Fermi GBM detection
  70. GRB 081124: Fermi GBM detection
  71. GRB 081120: Fermi GBM detection
  72. GRB 081118: Fermi GBM detection.
  73. GRB 081122: Fermi GBM detection
  74. Konus-Wind observation of GRB 081121
  75. GRB 081121, SMARTS optical/IR afterglow observations
  76. GRB081121: Fermi GBM detection
  77. Fermi GBM detection of a weak source
  78. GRB081121: Refined Swift/UVOT observations
  79. GRB 081121: Swift-XRT refined analysis
  80. GRB 081121: Magellan Redshift
  81. GRB 081121: Enhanced Swift-XRT position
  82. GRB 081121: GROND observations
  83. GRB 081121: Swift-BAT refined analysis
  84. GRB081121: Swift/UVOT observations
  85. GRB 081121: Swift detection of a burst
  86. GRB 081121: ROTSE-III Detection of Optical Counterpart
  87. GRB081118 : optical upper limit
  88. GRB 081016b, SMARTS optical/IR observations
  89. GRB 081119: Fermi GBM detection
  90. VLA Radio upper limit on GRB 081118
  91. GRB 081118: VLT redshift
  92. GRB 081118: Swift-XRT refined analysis
  93. GRB 081118: GROND detection of afterglow
  94. GRB 081118: optical afterglow candidate
  95. GRB 081118: Swift UVOT Upper Limits
  96. GRB 081118: Swift-BAT refined analysis
  97. GRB 081118: Enhanced Swift-XRT position
  98. GRB 081118: Swift detection of a burst
  99. GRB 081109A: confirmation of possible detection host galaxy
  100. Further Swift-XRT observations of the probable GRB 081105.

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