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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"

18733 results found.

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

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