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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 090929B: RAPTOR Discovery of Optical Counterpart
  2. GRB 090929A BAT location of the Fermi GBM burst
  3. Correction: GRB 090929B: Enhanced Swift-XRT position
  4. GRB 090929: Enhanced Swift-XRT position
  5. GRB 090929B: Swift detection of a burst
  6. GRB 090929A: Fermi GBM detection
  7. GRB090926A: Swift-XRT refined analysis
  8. GRB 090927: Faulkes Telescope South Detection of the Optical Afterglow
  9. Konus-Wind and Konus-RF observations of GRB 090926A
  10. GRB 090927: VLT redshift
  11. GRB 090926B: Fermi GBM detection
  12. GRB 090927: Zadko Telescope observations
  13. GRB 090927, Swift-BAT refined analysis of the possibly short burst
  14. Swift/UVOT observations of GRB 090927
  15. GRB 090926A: Skynet/PROMPT Continued Observations
  16. GRB 090927: Swift XRT refined analysis
  17. GRB 090926A: Suzaku WAM observation of the prompt emission
  18. GRB 090927: Enhanced Swift-XRT position
  19. GRB090926B: Swift/UVOT Upper Limits
  20. GRB090926A: Swift/UVOT observations
  21. GRB 090926B: VLT spectroscopy
  22. GRB 090927: Swift/UVOT detection of an optical afterglow
  23. GRB 090927: Swift detection of a short burst
  24. GRB 090926B: optical object in error circle
  25. GRB 090926B: MAXI GSC detection
  26. GRB 090926A: VLT/X-shooter redshift
  27. GRB 090926B: NOT optical observation
  28. GRB 090926B: Swift XRT refined analysis
  29. GRB 090926B: Swift-BAT refined analysis
  30. GRB 090926A: Swift/UVOT detection of an optical afterglow
  31. GRB 090926A: Skynet/PROMPT Discovery of the Optical Afterglow
  32. GRB090926A: UVOT-enhanced XRT position
  33. GRB 090926B: Swift detection of a burst
  34. GRB 090926: Fermi LAT detection
  35. GRB 090926: Fermi GBM detection
  36. GRB 090925: Fermi GBM detection
  37. GRB090904B : IRSF NIR upper limit
  38. GRB090922A: correction to Fermi location
  39. GRB 090922A: Fermi GBM detection
  40. Swift returns to normal operations
  41. GRB 090715B: Skynet/PROMPT Detections
  42. GRB 090726: Skynet/GORT Observations
  43. GRB 090916: Swift-XRT upper limit
  44. GRB 090807: Skynet/DSO Observations
  45. GRB 090915: GROND upper limits
  46. Swift-BAT temporarily off-line for a few days
  47. Short-Duration GRB 090916: Skynet/PROMPT Observations
  48. GRB 090915: SARA detection of afterglow candidate
  49. GRB 090912: optical observation
  50. GRB 090915: Swift/UVOT detection of an optical afterglow candidate
  51. GRB 090702: Skynet/GORT Observations
  52. GRB 090902B: Skynet/PROMPT Observations
  53. GRB 090916, Swift-BAT refined analysis
  54. GRB 090915: Swift-XRT detection of a fading X-ray counterpart
  55. GRB 090916: Swift detection of a short burst
  56. GRB 090915 Swift-BAT detection of a burst in ground analysis
  57. GRB 090827: Confirmation of the X-ray afterglow
  58. GRB 090912: Swift-XRT refined analysis
  59. GRB 090912, Swift-BAT refined analysis
  60. GRB 090912: Swift/UVOT Upper Limits
  61. GRB 090912 optical upper limit
  62. GRB 090912: Enhanced Swift-XRT position
  63. GRB 090912: Swift detection of a burst
  64. GRB 090910: Fermi GBM detection
  65. GRB 090814A: Skynet/DSO & GORT Observations
  66. GRB 090823: Swift XRT confirmation of the X-ray afterglow
  67. GRB 090904B: GROND detection of the optical afterglow
  68. GRB 090831A: Suzaku WAM observation of the prompt emission
  69. GRB 090904A: Swift/UVOT Refined Analysis
  70. GRB 090904B: Swift/UVOT Refined Analysis
  71. GRB 090902B: Suzaku WAM observation of the prompt emission
  72. GRB 090829A: Suzaku WAM observation of the prompt emission
  73. GRB 090904B: Fermi GBM detection
  74. GRB 090904A: Swift-XRT refined analysis
  75. GRB 090904B: Swift XRT Refined Analysis
  76. GRB 090904B: MOA-II Optical observation
  77. GRB 090904A: Enhanced Swift XRT position
  78. GRB 090904B: Swift-BAT refined analysis
  79. GRB 090902B: VLA radio detection
  80. GRB 090904A: Swift-BAT refined analysis
  81. GRB 090904B: Enhanced Swift-XRT position
  82. GRB090904A: Correction to enhanced XRT position
  83. GRB 090904A: Enhanced Swift-XRT position
  84. GRB 090904A: NOT observations
  85. GRB 090902B: WSRT Radio Observation
  86. GRB090904B: REM observations
  87. GRB 090904B: Swift detection of a burst
  88. GRB 090904A: ROTSE-III Optical Limits
  89. GRB 090904: Swift detection of a burst
  90. GRB 090902B: ROTSE-III Detection of Optical Afterglow
  91. GRB 090902B: Swift/UVOT refined analysis
  92. GRB090902B: Swift XRT refined analysis
  93. GRB 090902B: Faulkes Telescope North observations
  94. GRB 090902B: GROND NIR Afterglow Observations
  95. GRB 090902B: Gemini-N absorption redshift
  96. GRB 090902B: Fermi LAT and GBM refined analysis.
  97. GRB 090902B: Enhanced Swift-XRT position
  98. GRB 090902B: Optical afterglow candidate
  99. GRB090902B: Swift/UVOT observations
  100. GRB 090902B: Swift/XRT Afterglow Candidate

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