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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"

28052 results found.

  1. VLA Radio upper limit on GRB 081203A
  2. Swift-XRT observations of GRB 081203B
  3. GRB081203A: Swift-XRT refined analysis
  4. GRB 081203B: optical observations
  5. Swift/UVOT detection of GRB081203B
  6. GRB 081203B: Swift-XRT candidate afterglow.
  7. GRB 081203A: optical observations
  8. GRB081203A: Swift/UVOT grism redshift
  9. GRB 081203A: Burst detection from Swift-BAT slew data
  10. GRB 081203A: Swift-BAT refined analysis
  11. GRB 081203: Enhanced Swift-XRT position
  12. GRB 081130B: MASTER prompt optical observations
  13. GRB081203: optical observation
  14. GRB 081203: Swift detection of a burst with a bright optical counterpart
  15. GRB 081130B: Fermi GBM detection
  16. GRB 081130: Fermi GBM detection
  17. Swift Trigger 335971: Swift/UVOT Observations
  18. GRB 081126: afterglow photometry
  19. GRB 081126: Fermi GBM detection
  20. VLA Radio upper limit on GRB 081126
  21. GRB 081129: Fermi GBM detection
  22. GRB 081130: MASTER VWF prompt optical observations Fermi GRB
  23. GRB 081128A: optical observations
  24. Trigger 335971: Swift possible detection of a burst
  25. GRB081128: Swift/UVOT Upper Limits
  26. GRB 081122B: Fermi GBM Detection
  27. GRB 081128: Swift-XRT refined analysis
  28. GRB 081128: Liverpool Telescope afterglow confirmation
  29. GRB081128: optical observations
  30. GRB 081128: Swift-BAT refined analysis
  31. GRB 081128: Enhanced Swift-XRT position
  32. GRB 081128: Optical observation of xinglong TNT
  33. GRB 081128: Swift detection of a burst
  34. GRB081126: Afterglow photometry from Crni Vrh
  35. GRB 081126: GRT Optical Observation
  36. GRB 081127: Swift/UVOT Upper Limits
  37. GRB 081127: Swift-XRT refined analysis
  38. GRB 081127: Enhanced Swift-XRT position
  39. GRB 081127: Swift-BAT refined analysis
  40. GRB 081126: Swift-XRT refined analysis
  41. GRB 081127: Swift detection of a burst
  42. GRB 081126: Swift/UVOT Observations
  43. GRB 081126: optical observations
  44. GRB 081126: Swift-BAT refined analysis
  45. GRB 081126: Enhanced Swift-XRT position
  46. GRB 081126: TAROT Calern observatory optical observations
  47. GRB 081126: Swift detection of a burst
  48. GRB 081125: Fermi GBM detection
  49. GRB 081124: Fermi GBM detection
  50. GRB 081120: Fermi GBM detection
  51. GRB 081118: Fermi GBM detection.
  52. GRB 081122: Fermi GBM detection
  53. GRB 081121, SMARTS optical/IR afterglow observations
  54. Fermi GBM detection of a weak source
  55. GRB081121: Refined Swift/UVOT observations
  56. GRB 081121: Swift-XRT refined analysis
  57. GRB 081121: Enhanced Swift-XRT position
  58. GRB 081121: GROND observations
  59. GRB 081121: Swift-BAT refined analysis
  60. GRB081121: Swift/UVOT observations
  61. GRB 081121: ROTSE-III Detection of Optical Counterpart
  62. GRB081118 : optical upper limit
  63. GRB 081119: Fermi GBM detection
  64. VLA Radio upper limit on GRB 081118
  65. GRB 081118: Swift-XRT refined analysis
  66. GRB 081118: GROND detection of afterglow
  67. GRB 081118: optical afterglow candidate
  68. GRB 081118: Swift UVOT Upper Limits
  69. GRB 081118: Swift-BAT refined analysis
  70. GRB 081118: Enhanced Swift-XRT position
  71. GRB 081118: Swift detection of a burst
  72. GRB 081109A: confirmation of possible detection host galaxy
  73. Further Swift-XRT observations of the probable GRB 081105.
  74. GRB 081113: Fermi GBM detection
  75. GRB 081102: RTT150 Optical observations
  76. GRB 081110: Fermi GBM detection
  77. GRB 081109: TAROT La Silla observatory optical observations
  78. GRB 081102: MASTER refind and final results
  79. GRB 081109: GROND redshift limit and host extinction
  80. GRB 081025: Swift-XRT further analysis
  81. GRB 081024B: Swift-XRT late-time observations
  82. GRB 081109: GROND Detection of the Optical/NIR Afterglow Candidate
  83. GRB 081109A, Swift-BAT refined analysis
  84. GRB 081109A: Swift-XRT refined analysis
  85. GRB 081109: Fermi GBM detection
  86. Swift-BAT Trigger 334129: possible burst
  87. GRB 081109: REM NIR afterglow detection
  88. GRB 081109: Swift detection of a burst
  89. GRB 081024C: Fermi Gamma-ray Burst Monitor detection
  90. SGR 1806-20: Fermi GBM detection
  91. GRB 081102B: Fermi GBM detection
  92. GRB 081105B: Fermi GBM detection
  93. GRB 081107: Fermi GBM detection
  94. GRB 081104: GROND found no Optical/NIR Afterglow
  95. GRB 081105: GROND Upper Limits
  96. Radio observation of GRB 080523 with ATCA
  97. Radio observation of GRB 080520 with ATCA
  98. GRB 081105: Observations from OSN
  99. Swift-XRT observations of GRB 081105
  100. GRB 081101B: Fermi GBM detection

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Download all Circulars as a .tar.gz archive (updated once a day):
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