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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"

19264 results found.

  1. GRB 050922C: Swift-BAT refined analysis
  2. GRB 050922B: Swift-BAT refined analysis
  3. GRB050922C: optical observations
  4. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  5. GRB 050922C: optical obserations
  6. GRB 050922C: NOT optical observations
  7. GRB 050922A: Analysis of Swift/XRT TOO observation
  8. GRB 050922C: Swift detection of a bright burst
  9. GRB 050922C: ROTSE-IIId Refined Analysis
  10. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  11. GRB 050922B: ROTSE-III Optical Limits
  12. GRB 050922B,optical observation
  13. GRB050922B: Swift-BAT detection of a weak long burst
  14. GRB050918: Possible Swift/XRT detected afterglow
  15. GRB050820B: analysis of the XMM-Newton observation
  16. GRB050916: Swift/UVOT Upper Limits
  17. GRB 050916: Swift-BAT refined analysis
  18. Swift-BAT trigger 155764 is not a GRB
  19. Swift-BAT trigger 155764 is probably not a GRB
  20. Swift trigger 155764: bad XRT centroid
  21. Swift-BAT trigger 155535 is definitely not a GRB
  22. GRB050916 : Swift-XRT refined analysis
  23. GRB 050916: XRT position
  24. GRB 050915B: Swift-BAT refined analysis
  25. GRB 050915B: Swift/UVOT Upper Limits
  26. GRB050916: Swift-BAT detection of a long weak burst
  27. GRB 050915B: XRT position
  28. GRB050915B: Swift-BAT detection of a long bright burst
  29. GRB050915: Swift/UVOT upper limits
  30. GRB 050915: KAIT optical limit
  31. GRB 050915: IR Observations
  32. GRB 050915: Swift XRT refined analysis
  33. GRB 050915: Swift-BAT refined analysis
  34. GRB050915, optical observations
  35. GRB050915: XRT position
  36. GRB 050915: ROTSE-III optical limits
  37. GRB 050915: Swift detection of a GRB
  38. GRB050911: Upper limit on X-ray afterglow
  39. Swift-BAT trigger 155072 ground analysis
  40. Swift-BAT trigger 155072 is probably not a GRB
  41. GRB050914: XRT position probably due to cosmic ray
  42. Swift is in normal operation
  43. GRB050911: Swift UVOT followup observations
  44. GRB 050911, optical content of Swift/XRT error box
  45. GRB050911: Swift-XRT position
  46. GRB 050911, optical observations
  47. GRB 050911: Swift-BAT refined analysis
  48. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  49. GRB050911: Swift-BAT detection of a long burst
  50. GRB050908: detection of Swift/UVOT optical counterpart
  51. RBO GRB 050908 observations
  52. WIRO observations in I of GRB 050908
  53. GRB 050906: Possible X-ray Counterpart
  54. GRB050908: Swift/UVOT Early upper limits
  55. GRB050908 : Swift-XRT refined analysis
  56. GRB 050908: Swift-BAT refined analysis
  57. GRB 050908: Optical observations
  58. Gemini Spectroscopy of GRB 050908
  59. GRB 050908 : Swift XRT position
  60. GRB 050908: KAIT observations
  61. GRB 050908: P60 Confirmation of Optical Afterglow
  62. GRB 050908: Swift detection of a burst
  63. Swift trigger 154073 is not a GRB
  64. GRB050904: CrAO optical observations
  65. GRB 050904 BAT refined analysis of complete data set
  66. GRB 050906: MARGE Optical Limits
  67. GRB 050906: Swift-BAT refined analysis
  68. GRB 050906: Swift XRT upper limit
  69. GRB050906: P60 Observations
  70. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  71. GRB 050906: Bright galaxy in BAT error box
  72. GRB 050906: Swift/BAT Detection of a possible burst
  73. GRB 050904: Swift/UVOT observations
  74. GRB 050904: early Swift XRT analysis results
  75. GRB 050904: BAT refined analysis of partial data set
  76. GRB050904: P60 Observations
  77. GRB 050904: TAROT optical limits
  78. GRB050904: Swift-BAT detection of a probable burst
  79. Swift-BAT triggers 153461-153465 are not GRBs
  80. Retraction of Swift-BAT trigger #153355
  81. GRB 050824: MDM Observations
  82. GRB 050827: Swift XRT preliminary analysis results
  83. Swift Trigger #152652 is not a GRB
  84. GRB050827: Swift/UVOT upper limits
  85. GRB 050827: Optical Limit
  86. GRB 050827: XRT possible afterglow detection
  87. GRB050827: RTT150 optical observations
  88. GRB 050827: Swift-BAT refined analysis
  89. GRB050827: Swift-BAT detection of a burst
  90. GRB 050826: Optical Candidate
  91. GRB050824, HETE-2 Observation
  92. GRB 050826: Swift XRT preliminary analysis results
  93. GRB 050826: BAT refined analysis
  94. GRB050826: Swift/UVOT early upper limits
  95. GRB050824: First 2 hours of power low optical decay?
  96. GRB 050826: Swift XRT position
  97. GRB050826: Swift-BAT detection of a long burst
  98. GRB050824: MASTER final analysis of the OT observations
  99. Possible GRB050825:MASTER optical observations
  100. Swift-BAT trigger 152038 is definitely not a GRB

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