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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"

18693 results found.

  1. GRB 091029: Enhanced Swift-XRT position
  2. GRB 091029: Skynet/PROMPT Observations of Peak and Fading
  3. GRB 091029: GROND Detection of the Optical/NIR Afterglow
  4. GRB 091029: Swift detection of a burst with an optical counterpart
  5. A mistake in testing a new function in Swift
  6. GRB 091020: Fermi GBM observation
  7. GRB 091026: Suzaku WAM observation of the prompt emission
  8. GRB 091026: GROND Upper Limits
  9. GRB 091020: Late TLS detection
  10. GRB 091026: Swift-BAT refined analysis
  11. Radio afterglow detection from GRB 091020
  12. GRB 091026: Swift/UVOT Upper Limits
  13. GRB 091024: Burst was outside the Swift-BAT FOV after T0(BAT)+460sec
  14. GRB 091026: Swift-XRT refined analysis
  15. GRB 091026: Enhanced Swift-XRT position
  16. Konus-Wind and Konus-RF observations of GRB 091024
  17. GRB 091026: Updated Swift-XRT position
  18. GRB 091026: Swift detection of a Gamma Ray Burst
  19. Swift-BAT Triggers 373776-373778 are not real
  20. GRB091024 Swift/UVOT Upper Limits
  21. GRB 091024: TLS Upper Limit
  22. GRB 091020: Early TLS Multicolor detections, red afterglow
  23. GRB 091024: KAIT optical afterglow observations
  24. GRB 091024: Swift-BAT refined analysis
  25. Swift-BAT Triggers 373679-373684 are not real
  26. GRB 091024: Fermi GBM Observations
  27. GRB 091024: Swift-XRT team refined analysis
  28. Swift-BAT trigger 373691 is a galactic bulge transient
  29. GRB 091024 : Faulkes Telescope North - Afterglow Confirmation
  30. GRB 091024: Faulkes Telescope North Afterglow Candidate
  31. GRB 091024: Swift detection of a burst
  32. GRB 091020: Swift-XRT refined analysis
  33. GRB 091018: Swift XRT refined analysis
  34. GRB091020 Swift/UVOT observations
  35. GRB 091020, Swift-BAT refined analysis
  36. GRB 091020: Enhanced Swift-XRT position
  37. GRB 090926A: Late-time Gemini South Observations and Possible Jet Break
  38. GRB 091020: Swift detection of a burst with an optical afterglow
  39. GRB 091018: Skynet/PROMPT Observations of Fading
  40. Konus-RF observation of GRB 091018
  41. GRB 091018 : Faulkes Telescope South Observations
  42. GRB091018: Swift/UVOT observations
  43. GRB 091018: Swift-BAT refined analysis
  44. GRB 091018: Enhanced Swift-XRT position
  45. GRB 091018: ROTSE-III Detection of Optical Counterpart
  46. GRB 091018: Swift detection of a burst with optical afterglow
  47. GRB 090726 R band observations
  48. GRB 091010: Swift-XRT refined analysis
  49. Radio observation of GRB090927 with ATCA
  50. GRB 091010: Fermi GBM observation
  51. GRB 090531A: Skynet/PROMPT Observations
  52. GRB 090530A: Skynet/DSO Detections
  53. GRB 091010: Enhanced XRT position
  54. GRB 091010: GROND afterglow candidate
  55. GRB 091010: Swift/UVOT Upper Limits
  56. GRB 091010: Swift-XRT position
  57. GRB 090518: Skynet/PROMPT Observations
  58. Short-Duration GRB 090621: Skynet/Dolomiti Observations
  59. GRB 090812: Skynet/PROMPT and GORT Observations
  60. GRB 091003: Lick observations and possible SDSS host galaxy
  61. GRB 090926B: Skynet/PROMPT Observations
  62. GRB 090929B: Suzaku WAM observation of the prompt emission
  63. GRB 091003: Swift-XRT confirmation of fading afterglow
  64. GRB 091003: Swift/UVOT Detection of an Optical Afterglow
  65. GRB 091003: UVOT-enhanced XRT position
  66. GRB 091003: Swift UVOT Detection of a Candidate UV Afterglow
  67. GRB 091003: Swift XRT analysis
  68. GRB 091003A: Fermi LAT detection
  69. GRB 090929A: Swift/UVOT Observations
  70. GRB 090929A, Swift-BAT refined analysis
  71. GRB 090929B, Swift-BAT refined analysis
  72. Trigger 371210: Swift/BAT Triggered on IGR J17511-3057
  73. GRB 090929A: Swift-XRT non-detection
  74. Konus-Wind observation of GRB 090929A
  75. Konus-Wind observation of GRB 090929B
  76. GRB 090927: Fermi GBM observation
  77. GRB 090929B: Swift-XRT refined analysis
  78. GRB 090929B: Skynet/DSO Observations
  79. GRB 090929B: Swift/UVOT Observations
  80. Konus-RF observation of GRB 090929A
  81. GRB 090929B: RAPTOR Discovery of Optical Counterpart
  82. GRB 090929A BAT location of the Fermi GBM burst
  83. Correction: GRB 090929B: Enhanced Swift-XRT position
  84. GRB 090929: Enhanced Swift-XRT position
  85. GRB 090929B: Swift detection of a burst
  86. GRB090926A: Swift-XRT refined analysis
  87. GRB 090927: Faulkes Telescope South Detection of the Optical Afterglow
  88. GRB 090926B: Fermi GBM detection
  89. GRB 090927: Zadko Telescope observations
  90. GRB 090927, Swift-BAT refined analysis of the possibly short burst
  91. Swift/UVOT observations of GRB 090927
  92. GRB 090927: Swift XRT refined analysis
  93. GRB 090927: Enhanced Swift-XRT position
  94. GRB090926B: Swift/UVOT Upper Limits
  95. GRB090926A: Swift/UVOT observations
  96. GRB 090927: Swift/UVOT detection of an optical afterglow
  97. GRB 090927: Swift detection of a short burst
  98. GRB 090926B: MAXI GSC detection
  99. GRB 090926B: Swift XRT refined analysis
  100. GRB 090926B: Swift-BAT refined analysis

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