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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"

18399 results found.

  1. GRB 051008: Swift XRT position
  2. GRB 051008: early Swift XRT analysis
  3. GRB 051008: Swift UVOT Candidate
  4. GRB051008: Swift-BAT detection of a bright burst
  5. GRB 051006: XRT refined analysis
  6. Swift-BAT trigger 158700 is a probable Cosmic Ray Shower Event
  7. GRB 051006: optical observations at Sierra Nevada
  8. GRB051006: Refined analysis of the Swift-BAT burst
  9. GRB 051006: XRT position
  10. GRB051006: Swift detection of a burst
  11. Swift-BAT triggers 158261 and 158262 Retraction
  12. GRB051001: Swift UVOT Upper Limits
  13. GRB 050925: Second Epoch WSRT Radio Observations
  14. GRB 051001: Swift XRT refined analysis
  15. GRB 051001, optical observations at Mt. John
  16. GRB 051001: I-band limit
  17. GRB 051001: Swift-BAT refined analysis
  18. GRB 051001: Swift Detection of a Burst
  19. GRB 051001: ROTSE-III Optical Limits
  20. GRB050922B: optical limit
  21. GRB050925: Swift/XRT limits
  22. GRB/SGR 050925: IR Observations
  23. GRB050922C - Swift UVOT preliminary analysis
  24. GRB 050925: WSRT Radio Observations
  25. GRB050925: Swift UVOT upper limits
  26. Refined analysis of the Swift-BAT soft short burst
  27. GRB050925: Faulkes Telescope North R-band limit
  28. GRB050925: Swift-BAT detection of a short burst
  29. GRB 050922B: Correction to BAT refined analysis, longer burst
  30. GRB050922B: refined XRT analysis
  31. Konus-Wind observation of GRB 050922C
  32. GRB050922B: Swift UVOT early upper limits.
  33. GRB 050922B: optical limit
  34. GRB 050922C: Swift XRT refined analysis
  35. HETE Fregate observations of GRB 050922C
  36. GRB 050922C: Swift-BAT refined analysis
  37. GRB 050922B: Swift-BAT refined analysis
  38. GRB050922C: optical observations
  39. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  40. GRB 050922C: optical obserations
  41. GRB 050922C: NOT optical observations
  42. GRB 050922A: Analysis of Swift/XRT TOO observation
  43. GRB 050922C: Swift detection of a bright burst
  44. GRB 050922C: ROTSE-IIId Refined Analysis
  45. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  46. GRB 050922B: ROTSE-III Optical Limits
  47. GRB 050922B,optical observation
  48. GRB050922B: Swift-BAT detection of a weak long burst
  49. GRB050918: Possible Swift/XRT detected afterglow
  50. GRB050820B: analysis of the XMM-Newton observation
  51. GRB050916: Swift/UVOT Upper Limits
  52. GRB 050916: Swift-BAT refined analysis
  53. Swift-BAT trigger 155764 is not a GRB
  54. Swift-BAT trigger 155764 is probably not a GRB
  55. Swift trigger 155764: bad XRT centroid
  56. Swift-BAT trigger 155535 is definitely not a GRB
  57. GRB050916 : Swift-XRT refined analysis
  58. GRB 050916: XRT position
  59. GRB 050915B: Swift-BAT refined analysis
  60. GRB 050915B: Swift/UVOT Upper Limits
  61. GRB050916: Swift-BAT detection of a long weak burst
  62. GRB 050915B: XRT position
  63. GRB050915B: Swift-BAT detection of a long bright burst
  64. GRB050915: Swift/UVOT upper limits
  65. GRB 050915: KAIT optical limit
  66. GRB 050915: IR Observations
  67. GRB 050915: Swift XRT refined analysis
  68. GRB 050915: Swift-BAT refined analysis
  69. GRB050915, optical observations
  70. GRB050915: XRT position
  71. GRB 050915: ROTSE-III optical limits
  72. GRB 050915: Swift detection of a GRB
  73. GRB050911: Upper limit on X-ray afterglow
  74. Swift-BAT trigger 155072 ground analysis
  75. Swift-BAT trigger 155072 is probably not a GRB
  76. GRB050914: XRT position probably due to cosmic ray
  77. Swift is in normal operation
  78. GRB050911: Swift UVOT followup observations
  79. GRB 050911, optical content of Swift/XRT error box
  80. GRB050911: Swift-XRT position
  81. GRB 050911, optical observations
  82. GRB 050911: Swift-BAT refined analysis
  83. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  84. GRB050911: Swift-BAT detection of a long burst
  85. GRB050908: detection of Swift/UVOT optical counterpart
  86. RBO GRB 050908 observations
  87. WIRO observations in I of GRB 050908
  88. GRB 050906: Possible X-ray Counterpart
  89. GRB050908: Swift/UVOT Early upper limits
  90. GRB050908 : Swift-XRT refined analysis
  91. GRB 050908: Swift-BAT refined analysis
  92. GRB 050908: Optical observations
  93. Gemini Spectroscopy of GRB 050908
  94. GRB 050908 : Swift XRT position
  95. GRB 050908: KAIT observations
  96. GRB 050908: P60 Confirmation of Optical Afterglow
  97. GRB 050908: Swift detection of a burst
  98. Swift trigger 154073 is not a GRB
  99. GRB050904: CrAO optical observations
  100. GRB 050904 BAT refined analysis of complete data set

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