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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"

18397 results found.

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

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