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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"

19603 results found.

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

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