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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 091109B: ROTSE-III Optical Limits
  2. GRB 091109B: Swift detection of a short burst
  3. GRB091109: Correction to GCN 10139
  4. GRB 091030: Fermi GBM detection
  5. GRB 091109: Swift-XRT refined analysis
  6. GRB 091109: BOOTES-3 observations
  7. GRB 091109: Swift/UVOT observations
  8. GRB 091109: Faulkes Telescope South observations
  9. GRB 091109: Swift-BAT refined analysis
  10. GRB 091109: Enhanced Swift-XRT position
  11. GRB091109: REM detection of the NIR afterglow
  12. GRB 091109: Swift detection of a burst with optical afterglow
  13. GRB 091029: Observations from Stardome Observatory
  14. GRB 091104: Swift-BAT refined analysis
  15. GRB 091104: Swift XRT Refined Analysis
  16. GRB 091104: Swift/UVOT Upper Limits
  17. GRB091026 : IRSF NIR upper limit
  18. GRB091102 : MOA optical upper limit
  19. GRB 091104: Enhanced Swift-XRT position
  20. GRB 091104: Swift detection of a burst
  21. GRB 091102: LABOCA/APEX submm observations
  22. Fermi LAT Upper Limits on GRB 091010
  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: BOOTES-3 observations
  29. GRB 091102: Swift-BAT refined analysis
  30. GRB 091102: Swift/XRT localization
  31. GRB 091102: ROTSE-III Optical Limits
  32. GRB 091102: Swift/UVOT Finding Chart Observation
  33. GRB 091102: Swift detection of a burst
  34. GRB 091024: optical observations
  35. GRB 091031: Fermi GBM detection
  36. GRB 091024: Fermi LAT upper limits
  37. GRB 090926a, SMARTS optical/IR afterglow observations
  38. GRB 091018: Skynet/PROMPT Observations of Possible Host Galaxy
  39. GRB 091029, SMARTS optical/IR afterglow observations
  40. GRB 091018, SMARTS optical/IR afterglow observations
  41. GRB 090920: Skynet/DSO Detection
  42. GRB091029: Swift/UVOT observations
  43. GRB 091029: Skynet/PROMPT Continued Observations of Fading
  44. GRB 091029: Swift XRT refined analysis
  45. Fermi Gamma-ray Burst Monitor trigger 091028818 is not a GRB
  46. GRB 091029: BOOTES-3 observations
  47. GRB 091029: Swift-BAT refined analysis
  48. GRB 091029: Enhanced Swift-XRT position
  49. GRB091024 optical observations
  50. GRB 091029: Gemini-South Redshift
  51. GRB 091029: Skynet/PROMPT Observations of Peak and Fading
  52. GRB 091029: GROND Detection of the Optical/NIR Afterglow
  53. GRB 091029: Swift detection of a burst with an optical counterpart
  54. A mistake in testing a new function in Swift
  55. GRB 091020: Fermi GBM observation
  56. GRB 091026: Suzaku WAM observation of the prompt emission
  57. GRB 091024: Keck/LRIS Spectroscopy
  58. GRB 091024: YNAO-GMG observations
  59. GRB 091026: GROND Upper Limits
  60. GRB 091020: Late TLS detection
  61. GRB 091026: Swift-BAT refined analysis
  62. Radio afterglow detection from GRB 091020
  63. GRB 091026: Swift/UVOT Upper Limits
  64. GRB 091024: Burst was outside the Swift-BAT FOV after T0(BAT)+460sec
  65. GRB 091026: Swift-XRT refined analysis
  66. GRB 091026: Enhanced Swift-XRT position
  67. Konus-Wind and Konus-RF observations of GRB 091024
  68. GRB 091026: Updated Swift-XRT position
  69. GRB 091026: Swift detection of a Gamma Ray Burst
  70. GRB 091020 : Xinglong TNT upper limit
  71. Swift-BAT Triggers 373776-373778 are not real
  72. GRB091024 Swift/UVOT Upper Limits
  73. GRB 091024: TLS Upper Limit
  74. GRB 091020: Early TLS Multicolor detections, red afterglow
  75. GRB 091024: KAIT optical afterglow observations
  76. GRB 091024: Super-LOTIS early observations
  77. GRB091024: VRcIc Afterglow Observations
  78. GRB 091024: Swift-BAT refined analysis
  79. Swift-BAT Triggers 373679-373684 are not real
  80. GRB 091024: Fermi GBM Observations
  81. GRB 091024: Swift-XRT team refined analysis
  82. Swift-BAT trigger 373691 is a galactic bulge transient
  83. GRB 091024: Xinglong TNT optical observation
  84. GRB 091024 : Faulkes Telescope North - Afterglow Confirmation
  85. GRB 091024 Gemini-North redshift
  86. GRB 091024: GRAS004 optical observations
  87. GRB 091024: Faulkes Telescope North Afterglow Candidate
  88. GRB 091024: Swift detection of a burst
  89. GRB 091018: Skynet/PROMPT Continued Observations of Fading
  90. GRB 091020: Additional Lick observations
  91. Konus-Wind observations of GRB 091020 (correction to GCN 10057)
  92. GRB 091020: Lick observations
  93. Konus-Wind observations of GRB 091010
  94. GRB 091020: Swift-XRT refined analysis
  95. GRB 091018: Swift XRT refined analysis
  96. GRB091020 Swift/UVOT observations
  97. GRB 091020: NOT spectroscopic redshift
  98. GRB 091020: MASTER optical transient polarimetry
  99. GRB 091020, Swift-BAT refined analysis
  100. GRB 091020: Enhanced Swift-XRT position

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