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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"

19598 results found.

  1. GRB 051006: XRT refined analysis
  2. Swift-BAT trigger 158700 is a probable Cosmic Ray Shower Event
  3. GRB 051006: optical observations at Sierra Nevada
  4. GRB051006: Refined analysis of the Swift-BAT burst
  5. GRB 051006: XRT position
  6. GRB051006: Swift detection of a burst
  7. Swift-BAT triggers 158261 and 158262 Retraction
  8. GRB051001: Swift UVOT Upper Limits
  9. GRB 050925: Second Epoch WSRT Radio Observations
  10. GRB 051001: Swift XRT refined analysis
  11. GRB 051001, optical observations at Mt. John
  12. GRB 051001: I-band limit
  13. GRB 051001: Swift-BAT refined analysis
  14. GRB 051001: Swift Detection of a Burst
  15. GRB 051001: ROTSE-III Optical Limits
  16. GRB050922B: optical limit
  17. GRB050925: Swift/XRT limits
  18. GRB/SGR 050925: IR Observations
  19. GRB050922C - Swift UVOT preliminary analysis
  20. GRB 050925: WSRT Radio Observations
  21. GRB050925: Swift UVOT upper limits
  22. Refined analysis of the Swift-BAT soft short burst
  23. GRB050925: Faulkes Telescope North R-band limit
  24. GRB050925: Swift-BAT detection of a short burst
  25. GRB 050922B: Correction to BAT refined analysis, longer burst
  26. GRB050922B: refined XRT analysis
  27. Konus-Wind observation of GRB 050922C
  28. GRB050922B: Swift UVOT early upper limits.
  29. GRB 050922B: optical limit
  30. GRB 050922C: Swift XRT refined analysis
  31. HETE Fregate observations of GRB 050922C
  32. GRB 050922C: Swift-BAT refined analysis
  33. GRB 050922B: Swift-BAT refined analysis
  34. GRB050922C: optical observations
  35. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  36. GRB 050922C: optical obserations
  37. GRB 050922C: NOT optical observations
  38. GRB 050922A: Analysis of Swift/XRT TOO observation
  39. GRB 050922C: Swift detection of a bright burst
  40. GRB 050922C: ROTSE-IIId Refined Analysis
  41. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  42. GRB 050922B: ROTSE-III Optical Limits
  43. GRB 050922B,optical observation
  44. GRB050922B: Swift-BAT detection of a weak long burst
  45. GRB050918: Possible Swift/XRT detected afterglow
  46. GRB050820B: analysis of the XMM-Newton observation
  47. GRB050916: Swift/UVOT Upper Limits
  48. GRB 050916: Swift-BAT refined analysis
  49. Swift-BAT trigger 155764 is not a GRB
  50. Swift-BAT trigger 155764 is probably not a GRB
  51. Swift trigger 155764: bad XRT centroid
  52. Swift-BAT trigger 155535 is definitely not a GRB
  53. GRB050916 : Swift-XRT refined analysis
  54. GRB 050916: XRT position
  55. GRB 050915B: Swift-BAT refined analysis
  56. GRB 050915B: Swift/UVOT Upper Limits
  57. GRB050916: Swift-BAT detection of a long weak burst
  58. GRB 050915B: XRT position
  59. GRB050915B: Swift-BAT detection of a long bright burst
  60. GRB050915: Swift/UVOT upper limits
  61. GRB 050915: KAIT optical limit
  62. GRB 050915: IR Observations
  63. GRB 050915: Swift XRT refined analysis
  64. GRB 050915: Swift-BAT refined analysis
  65. GRB050915, optical observations
  66. GRB050915: XRT position
  67. GRB 050915: ROTSE-III optical limits
  68. GRB 050915: Swift detection of a GRB
  69. GRB050911: Upper limit on X-ray afterglow
  70. Swift-BAT trigger 155072 ground analysis
  71. Swift-BAT trigger 155072 is probably not a GRB
  72. GRB050914: XRT position probably due to cosmic ray
  73. Swift is in normal operation
  74. GRB050911: Swift UVOT followup observations
  75. GRB 050911, optical content of Swift/XRT error box
  76. GRB050911: Swift-XRT position
  77. GRB 050911, optical observations
  78. GRB 050911: Swift-BAT refined analysis
  79. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  80. GRB050911: Swift-BAT detection of a long burst
  81. GRB050908: detection of Swift/UVOT optical counterpart
  82. RBO GRB 050908 observations
  83. WIRO observations in I of GRB 050908
  84. GRB 050906: Possible X-ray Counterpart
  85. GRB050908: Swift/UVOT Early upper limits
  86. GRB050908 : Swift-XRT refined analysis
  87. GRB 050908: Swift-BAT refined analysis
  88. GRB 050908: Optical observations
  89. Gemini Spectroscopy of GRB 050908
  90. GRB 050908 : Swift XRT position
  91. GRB 050908: KAIT observations
  92. GRB 050908: P60 Confirmation of Optical Afterglow
  93. GRB 050908: Swift detection of a burst
  94. Swift trigger 154073 is not a GRB
  95. GRB050904: CrAO optical observations
  96. GRB 050904 BAT refined analysis of complete data set
  97. GRB 050906: MARGE Optical Limits
  98. GRB 050906: Swift-BAT refined analysis
  99. GRB 050906: Swift XRT upper limit
  100. GRB050906: P60 Observations

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