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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"

21393 results found.

  1. GRB 050906, summary of radio observations
  2. Swift-BAT triggers 158261 and 158262 Retraction
  3. GRB051001: Swift UVOT Upper Limits
  4. GRB 050925: Second Epoch WSRT Radio Observations
  5. GRB 051001: Swift XRT refined analysis
  6. GRB 051001, optical observations at Mt. John
  7. GRB 051001: I-band limit
  8. GRB 051001: AAT infra-red observations
  9. GRB 051001: Swift-BAT refined analysis
  10. GRB 051001: Swift Detection of a Burst
  11. GRB 051001: ROTSE-III Optical Limits
  12. GRB050922B: optical limit
  13. GRB050925: Swift/XRT limits
  14. GRB/SGR 050925: IR Observations
  15. GRB050922C - Swift UVOT preliminary analysis
  16. GRB 050925: WSRT Radio Observations
  17. GRB050925: Swift UVOT upper limits
  18. Refined analysis of the Swift-BAT soft short burst
  19. GRB050925: Faulkes Telescope North R-band limit
  20. GRB050925: Swift-BAT detection of a short burst
  21. GRB 050922B: Correction to BAT refined analysis, longer burst
  22. GRB050922B: refined XRT analysis
  23. Konus-Wind observation of GRB 050922C
  24. GRB050922B: Swift UVOT early upper limits.
  25. INT 2.5m limit for GRB050922B
  26. GRB 050922B: optical limit
  27. GRB 050922C: Swift XRT refined analysis
  28. HETE Fregate observations of GRB 050922C
  29. GRB 050922C: Swift-BAT refined analysis
  30. GRB 050922B: Swift-BAT refined analysis
  31. GRB050922C: optical observations
  32. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  33. GRB 050922C: optical obserations
  34. GRB 050922C: NOT optical observations
  35. GRB 050922A: Analysis of Swift/XRT TOO observation
  36. GRB 050922C: Swift detection of a bright burst
  37. GRB 050922C: ROTSE-IIId Refined Analysis
  38. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  39. GRB 050922B: ROTSE-III Optical Limits
  40. GRB 050922B,optical observation
  41. GRB050922B: Swift-BAT detection of a weak long burst
  42. GRB050918: Possible Swift/XRT detected afterglow
  43. GRB050820B: analysis of the XMM-Newton observation
  44. GRB050916: Swift/UVOT Upper Limits
  45. GRB 050916: Swift-BAT refined analysis
  46. GRB 050915a: Radio Observations
  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, SMARTS optical/IR observations of the XRT position
  54. GRB 050915B: Swift-BAT refined analysis
  55. GRB 050915B: Swift/UVOT Upper Limits
  56. GRB050916: Swift-BAT detection of a long weak burst
  57. GRB 050915a: IR Transient
  58. GRB 050915B: XRT position
  59. GRB050915B: Swift-BAT detection of a long bright burst
  60. GRB050915: Swift/UVOT upper limits
  61. GRB 050915: KAIT optical limit
  62. GRB 050915: IR Observations
  63. GRB 050915: Swift XRT refined analysis
  64. GRB 050915: Swift-BAT refined analysis
  65. GRB050915: P60 Optical Observations
  66. GRB050915, optical observations
  67. GRB050915: XRT position
  68. GRB 050915: ROTSE-III optical limits
  69. GRB 050915: Swift detection of a GRB
  70. GRB050911: Upper limit on X-ray afterglow
  71. Swift-BAT trigger 155072 ground analysis
  72. Swift-BAT trigger 155072 is probably not a GRB
  73. GRB050914: XRT position probably due to cosmic ray
  74. GRB 050911: LCO limits on a variable source
  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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