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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"

19534 results found.

  1. GRB 091112: Swift-BAT refined analysis
  2. GRB 091112: Fermi GBM observation
  3. GRB 091112: Swift detection of a possible burst
  4. GRB 091109B: Swift/UVOT Upper Limits
  5. GRB 091109B: Swift-XRT Team refined analysis
  6. GRB 091109B: Swift-BAT refined analysis
  7. GRB 091109B: Enhanced Swift-XRT position
  8. GRB 091109B: ROTSE-III Optical Limits
  9. GRB 091109B: Swift detection of a short burst
  10. GRB 091109: Swift-XRT refined analysis
  11. GRB 091109: Swift/UVOT observations
  12. GRB 091109: Swift-BAT refined analysis
  13. GRB 091109: Enhanced Swift-XRT position
  14. GRB 091109: Swift detection of a burst with optical afterglow
  15. GRB 091029: Observations from Stardome Observatory
  16. GRB 091104: Swift-BAT refined analysis
  17. GRB 091104: Swift XRT Refined Analysis
  18. GRB 091104: Swift/UVOT Upper Limits
  19. GRB091026 : IRSF NIR upper limit
  20. GRB091102 : MOA optical upper limit
  21. GRB 091104: Enhanced Swift-XRT position
  22. GRB 091104: Swift detection of a burst
  23. GRB 091102 : Faulkes Telescope South Upper Limits
  24. GRB 091102A: Fermi GBM observation
  25. GRB 091102: Swift-XRT refined analysis
  26. GRB 091102: Swift/UVOT Upper Limits
  27. GRB 091102: GROND Upper Limits
  28. GRB 091102: Swift-BAT refined analysis
  29. GRB 091102: Swift/XRT localization
  30. GRB 091102: ROTSE-III Optical Limits
  31. GRB 091102: Swift/UVOT Finding Chart Observation
  32. GRB 091102: Swift detection of a burst
  33. GRB 091024: optical observations
  34. GRB 091024: Fermi LAT upper limits
  35. GRB 090920: Skynet/DSO Detection
  36. GRB091029: Swift/UVOT observations
  37. GRB 091029: Swift XRT refined analysis
  38. GRB 091029: Swift-BAT refined analysis
  39. GRB 091029: Enhanced Swift-XRT position
  40. GRB 091029: Skynet/PROMPT Observations of Peak and Fading
  41. GRB 091029: GROND Detection of the Optical/NIR Afterglow
  42. GRB 091029: Swift detection of a burst with an optical counterpart
  43. A mistake in testing a new function in Swift
  44. GRB 091020: Fermi GBM observation
  45. GRB 091026: Suzaku WAM observation of the prompt emission
  46. GRB 091026: GROND Upper Limits
  47. GRB 091020: Late TLS detection
  48. GRB 091026: Swift-BAT refined analysis
  49. Radio afterglow detection from GRB 091020
  50. GRB 091026: Swift/UVOT Upper Limits
  51. GRB 091024: Burst was outside the Swift-BAT FOV after T0(BAT)+460sec
  52. GRB 091026: Swift-XRT refined analysis
  53. GRB 091026: Enhanced Swift-XRT position
  54. Konus-Wind and Konus-RF observations of GRB 091024
  55. GRB 091026: Updated Swift-XRT position
  56. GRB 091026: Swift detection of a Gamma Ray Burst
  57. Swift-BAT Triggers 373776-373778 are not real
  58. GRB091024 Swift/UVOT Upper Limits
  59. GRB 091024: TLS Upper Limit
  60. GRB 091020: Early TLS Multicolor detections, red afterglow
  61. GRB 091024: KAIT optical afterglow observations
  62. GRB 091024: Swift-BAT refined analysis
  63. Swift-BAT Triggers 373679-373684 are not real
  64. GRB 091024: Fermi GBM Observations
  65. GRB 091024: Swift-XRT team refined analysis
  66. Swift-BAT trigger 373691 is a galactic bulge transient
  67. GRB 091024 : Faulkes Telescope North - Afterglow Confirmation
  68. GRB 091024: Faulkes Telescope North Afterglow Candidate
  69. GRB 091024: Swift detection of a burst
  70. GRB 091020: Swift-XRT refined analysis
  71. GRB 091018: Swift XRT refined analysis
  72. GRB091020 Swift/UVOT observations
  73. GRB 091020, Swift-BAT refined analysis
  74. GRB 091020: Enhanced Swift-XRT position
  75. GRB 090926A: Late-time Gemini South Observations and Possible Jet Break
  76. GRB 091020: Swift detection of a burst with an optical afterglow
  77. GRB 091018: Skynet/PROMPT Observations of Fading
  78. Konus-RF observation of GRB 091018
  79. GRB 091018 : Faulkes Telescope South Observations
  80. GRB091018: Swift/UVOT observations
  81. GRB 091018: Swift-BAT refined analysis
  82. GRB 091018: Enhanced Swift-XRT position
  83. GRB 091018: ROTSE-III Detection of Optical Counterpart
  84. GRB 091018: Swift detection of a burst with optical afterglow
  85. GRB 090726 R band observations
  86. GRB 091010: Swift-XRT refined analysis
  87. Radio observation of GRB090927 with ATCA
  88. GRB 091010: Fermi GBM observation
  89. GRB 090531A: Skynet/PROMPT Observations
  90. GRB 090530A: Skynet/DSO Detections
  91. GRB 091010: Enhanced XRT position
  92. GRB 091010: GROND afterglow candidate
  93. GRB 091010: Swift/UVOT Upper Limits
  94. GRB 091010: Swift-XRT position
  95. GRB 090518: Skynet/PROMPT Observations
  96. Short-Duration GRB 090621: Skynet/Dolomiti Observations
  97. GRB 090812: Skynet/PROMPT and GORT Observations
  98. GRB 091003: Lick observations and possible SDSS host galaxy
  99. GRB 090926B: Skynet/PROMPT Observations
  100. GRB 090929B: Suzaku WAM observation of the prompt emission

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