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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"
  1. GRB 050922C: break in the lightcurve
  2. GRB 050925: WSRT Radio Observations
  3. GRB050925: Swift UVOT upper limits
  4. Refined analysis of the Swift-BAT soft short burst
  5. GRB 050925 : I-band observation at Xinglong observatory
  6. GRB050925: Faulkes Telescope North R-band limit
  7. GRB050925: Swift-BAT detection of a short burst
  8. GRB 050922B: Correction to BAT refined analysis, longer burst
  9. GRB050922C: TNG spectroscopic observations
  10. GRB050922B: refined XRT analysis
  11. Konus-Wind observation of GRB 050922C
  12. GRB 050922C: Refined redshift
  13. GRB050922B: Swift UVOT early upper limits.
  14. GRB OT observation
  15. GRB050922C: observation at MonteBoo
  16. INT 2.5m limit for GRB050922B
  17. GRB 050922B: optical limit
  18. GRB050922C: Optical Observations
  19. GRB 050922C: Swift XRT refined analysis
  20. HETE Fregate observations of GRB 050922C
  21. GRB 050922C: Swift-BAT refined analysis
  22. GRB 050922B: Swift-BAT refined analysis
  23. GRB050922C: optical observations
  24. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  25. GRB 050922C: optical obserations
  26. GRB 050922C: NOT optical observations
  27. GRB 050922A: Analysis of Swift/XRT TOO observation
  28. GRB 050922C: Swift detection of a bright burst
  29. GRB 050922C: ROTSE-IIId Refined Analysis
  30. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  31. GRB 050922B: ROTSE-III Optical Limits
  32. GRB 050922B,optical observation
  33. GRB050922B: Swift-BAT detection of a weak long burst
  34. Possible GRB 050922 detected by INTEGRAL
  35. GRB050918: Possible Swift/XRT detected afterglow
  36. GRB050820B: analysis of the XMM-Newton observation
  37. GRB050916: Swift/UVOT Upper Limits
  38. GRB 050916: Swift-BAT refined analysis
  39. GRB 050918 - A long GRB detected by INTEGRAL
  40. GRB 050915a: Radio Observations
  41. Swift-BAT trigger 155764 is not a GRB
  42. Swift-BAT trigger 155764 is probably not a GRB
  43. Swift trigger 155764: bad XRT centroid
  44. Swift-BAT trigger 155535 is definitely not a GRB
  45. GRB050916 : Swift-XRT refined analysis
  46. GRB 050916: XRT position
  47. GRB 050915b, SMARTS optical/IR observations of the XRT position
  48. GRB 050915B: Swift-BAT refined analysis
  49. GRB 050915B: Swift/UVOT Upper Limits
  50. GRB050916: Swift-BAT detection of a long weak burst
  51. GRB 050915a: IR Transient
  52. GRB 050915B: XRT position
  53. GRB 050915b, SMARTS optical/IR observations
  54. GRB050915B: Swift-BAT detection of a long bright burst
  55. GRB050915: Swift/UVOT upper limits
  56. GRB 050915: KAIT optical limit
  57. GRB 050915: IR Observations
  58. GRB 050915: Swift XRT refined analysis
  59. GRB 050915: Swift-BAT refined analysis
  60. GRB050915: P60 Optical Observations
  61. GRB050915, optical observations
  62. GRB050915: XRT position
  63. GRB 050915: ROTSE-III optical limits
  64. GRB 050915: Swift detection of a GRB
  65. GRB050911: Upper limit on X-ray afterglow
  66. Swift-BAT trigger 155072 ground analysis
  67. Swift-BAT trigger 155072 is probably not a GRB
  68. GRB050914: XRT position probably due to cosmic ray
  69. GRB 050911: LCO limits on a variable source
  70. GRB 050908: DEIMOS spectrum and further analysis
  71. Swift is in normal operation
  72. GRB050911: Swift UVOT followup observations
  73. GRB 050911, optical content of Swift/XRT error box
  74. GRB050911: Swift-XRT position
  75. GRB 050911: LCO observations
  76. GRB 050911, optical observations
  77. GRB 050911: Swift-BAT refined analysis
  78. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  79. GRB 050911: z~0.16 cluster in the field
  80. GRB050911: Swift-BAT detection of a long burst
  81. GRB050908: detection of Swift/UVOT optical counterpart
  82. GRB 050910a: TAROT early optical limits
  83. RBO GRB 050908 observations
  84. WIRO observations in I of GRB 050908
  85. GRB 050906: Possible X-ray Counterpart
  86. GRB 050906: RTT150 optical observations
  87. GRB050908: Swift/UVOT Early upper limits
  88. GRB050908: VLT R-band decay index.
  89. GRB050908 : Swift-XRT refined analysis
  90. GRB 050908: Swift-BAT refined analysis
  91. GRB 050908: Optical observations
  92. Gemini Spectroscopy of GRB 050908
  93. GRB 050908: spectroscopic redshift
  94. GRB 050908: Prompt PROMPT Observations
  95. GRB 050908 : Swift XRT position
  96. GRB 050908: KAIT observations
  97. GRB 050908: P60 Confirmation of Optical Afterglow
  98. GRB 050908: Optical Observations
  99. GRB 050908: Swift detection of a burst
  100. Swift trigger 154073 is not a GRB

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