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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 090926B: Swift XRT refined analysis
  2. GRB 090926B: Swift-BAT refined analysis
  3. GRB 090926A: Swift/UVOT detection of an optical afterglow
  4. GRB 090926A: Skynet/PROMPT Discovery of the Optical Afterglow
  5. GRB090926A: UVOT-enhanced XRT position
  6. GRB 090926B: Swift detection of a burst
  7. GRB 090926: Fermi LAT detection
  8. GRB 090926: Fermi GBM detection
  9. GRB 090925: Fermi GBM detection
  10. GRB090904B : IRSF NIR upper limit
  11. GRB090922A: correction to Fermi location
  12. GRB 090922A: Fermi GBM detection
  13. Swift returns to normal operations
  14. GRB 090715B: Skynet/PROMPT Detections
  15. GRB 090726: Skynet/GORT Observations
  16. GRB 090916: Swift-XRT upper limit
  17. GRB 090807: Skynet/DSO Observations
  18. GRB 090915: GROND upper limits
  19. Swift-BAT temporarily off-line for a few days
  20. Short-Duration GRB 090916: Skynet/PROMPT Observations
  21. GRB 090915: SARA detection of afterglow candidate
  22. GRB 090912: optical observation
  23. GRB 090915: Swift/UVOT detection of an optical afterglow candidate
  24. GRB 090702: Skynet/GORT Observations
  25. GRB 090902B: Skynet/PROMPT Observations
  26. GRB 090916, Swift-BAT refined analysis
  27. GRB 090915: Swift-XRT detection of a fading X-ray counterpart
  28. GRB 090916: Swift detection of a short burst
  29. GRB 090915 Swift-BAT detection of a burst in ground analysis
  30. GRB 090827: Confirmation of the X-ray afterglow
  31. GRB 090912: Swift-XRT refined analysis
  32. GRB 090912, Swift-BAT refined analysis
  33. GRB 090912: Swift/UVOT Upper Limits
  34. GRB 090912 optical upper limit
  35. GRB 090912: Enhanced Swift-XRT position
  36. GRB 090912: Swift detection of a burst
  37. GRB 090910: Fermi GBM detection
  38. GRB 090814A: Skynet/DSO & GORT Observations
  39. GRB 090823: Swift XRT confirmation of the X-ray afterglow
  40. GRB 090904B: GROND detection of the optical afterglow
  41. GRB 090831A: Suzaku WAM observation of the prompt emission
  42. GRB 090904A: Swift/UVOT Refined Analysis
  43. GRB 090904B: Swift/UVOT Refined Analysis
  44. GRB 090902B: Suzaku WAM observation of the prompt emission
  45. GRB 090829A: Suzaku WAM observation of the prompt emission
  46. GRB 090904B: Fermi GBM detection
  47. GRB 090904A: Swift-XRT refined analysis
  48. GRB 090904B: Swift XRT Refined Analysis
  49. GRB 090904B: MOA-II Optical observation
  50. GRB 090904A: Enhanced Swift XRT position
  51. GRB 090904B: Swift-BAT refined analysis
  52. GRB 090902B: VLA radio detection
  53. GRB 090904A: Swift-BAT refined analysis
  54. GRB 090904B: Enhanced Swift-XRT position
  55. GRB090904A: Correction to enhanced XRT position
  56. GRB 090904A: Enhanced Swift-XRT position
  57. GRB 090904A: NOT observations
  58. GRB 090902B: WSRT Radio Observation
  59. GRB090904B: REM observations
  60. GRB 090904B: Swift detection of a burst
  61. GRB 090904A: ROTSE-III Optical Limits
  62. GRB 090904: Swift detection of a burst
  63. GRB 090902B: ROTSE-III Detection of Optical Afterglow
  64. GRB 090902B: Swift/UVOT refined analysis
  65. GRB090902B: Swift XRT refined analysis
  66. GRB 090902B: Faulkes Telescope North observations
  67. GRB 090902B: GROND NIR Afterglow Observations
  68. GRB 090902B: Gemini-N absorption redshift
  69. GRB 090902B: Fermi LAT and GBM refined analysis.
  70. GRB 090902B: Enhanced Swift-XRT position
  71. GRB 090902B: Optical afterglow candidate
  72. GRB090902B: Swift/UVOT observations
  73. GRB 090902B: Swift/XRT Afterglow Candidate
  74. GRB 090902B: Fermi LAT detection
  75. GRB 090902B: Fermi GBM detection of a bright burst
  76. GRB 090902: Fermi GBM detection
  77. GRB 090831A: IPN Triangulation
  78. GRB 090831C BAT refined analysis
  79. GRB 090831C: GROND upper limits
  80. Konus-Wind observations of GRB 090831A
  81. Swift Trigger 361477, called GRB090831B, is probably not real.
  82. GRB090831C: Swift/UVOT upper limits
  83. GRB 090831B: MITSuME optical upper limits
  84. GRB 090831C: Swift XRT Refined Analysis
  85. GRB 090829B: Fermi GBM Detection
  86. GRB 090831C: Enhanced Swift-XRT position
  87. GRB 090831C: Swift detection of a burst
  88. GRB 090831B, RIMOTS optical upper limits
  89. GRB 090831: MAXI GSC detection
  90. GRB 090831B: Swift detection of a possible burst
  91. GRB 090831: Fermi GBM detection
  92. GRB090829: Fermi GBM Detection
  93. Konus-Wind observations of GRB 090827
  94. GRB 090827: Swift XRT and UVOT observations
  95. GRB 090827 Burst discovered in BAT ground analysis
  96. GRB 090826: Fermi GBM detection
  97. GRB 090828: Fermi GBM detection
  98. Fermi Gamma-ray Burst Monitor trigger 273123112 is not a GRB
  99. GRB 090817 - TLS Observations
  100. GRB090817: Keck/LRIS Spectroscopy

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