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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"

19593 results found.

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

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