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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. GRB051006: Refined analysis of the Swift-BAT burst
  2. GRB 051006: XRT position
  3. GRB051006: Swift detection of a burst
  4. GRB 050906, summary of radio observations
  5. Swift-BAT triggers 158261 and 158262 Retraction
  6. GRB051001: Swift UVOT Upper Limits
  7. GRB 050925: Second Epoch WSRT Radio Observations
  8. GRB 051001: Swift XRT refined analysis
  9. GRB 051001, optical observations at Mt. John
  10. GRB 051001: I-band limit
  11. GRB 051001: AAT infra-red observations
  12. GRB 051001: Swift-BAT refined analysis
  13. GRB 051001: Swift Detection of a Burst
  14. GRB 051001: ROTSE-III Optical Limits
  15. GRB050908: optical observations
  16. GRB050922C: optical observation
  17. GRB050922B: optical limit
  18. GRB 050922C: further VLT observations
  19. GRB 050820A: NIR photometry at the TNG
  20. GRB050922C: UVES/VLT high resolution spectroscopy
  21. GRB050925: Swift/XRT limits
  22. GRB/SGR 050925: IR Observations
  23. GRB050922C - Swift UVOT preliminary analysis
  24. GRB 050922C: break in the lightcurve
  25. GRB 050925: WSRT Radio Observations
  26. GRB050925: Swift UVOT upper limits
  27. Refined analysis of the Swift-BAT soft short burst
  28. GRB 050925 : I-band observation at Xinglong observatory
  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. GRB050922C: TNG spectroscopic observations
  33. GRB050922B: refined XRT analysis
  34. Konus-Wind observation of GRB 050922C
  35. GRB 050922C: Refined redshift
  36. GRB050922B: Swift UVOT early upper limits.
  37. GRB OT observation
  38. GRB050922C: observation at MonteBoo
  39. INT 2.5m limit for GRB050922B
  40. GRB 050922B: optical limit
  41. GRB050922C: Optical Observations
  42. GRB 050922C: Swift XRT refined analysis
  43. HETE Fregate observations of GRB 050922C
  44. GRB 050922C: Swift-BAT refined analysis
  45. GRB 050922B: Swift-BAT refined analysis
  46. GRB050922C: optical observations
  47. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  48. GRB 050922C: optical obserations
  49. GRB 050922C: NOT optical observations
  50. GRB 050922A: Analysis of Swift/XRT TOO observation
  51. GRB 050922C: Swift detection of a bright burst
  52. GRB 050922C: ROTSE-IIId Refined Analysis
  53. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  54. GRB 050922B: ROTSE-III Optical Limits
  55. GRB 050922B,optical observation
  56. GRB050922B: Swift-BAT detection of a weak long burst
  57. Possible GRB 050922 detected by INTEGRAL
  58. GRB050918: Possible Swift/XRT detected afterglow
  59. GRB050820B: analysis of the XMM-Newton observation
  60. GRB050916: Swift/UVOT Upper Limits
  61. GRB 050916: Swift-BAT refined analysis
  62. GRB 050918 - A long GRB detected by INTEGRAL
  63. GRB 050915a: Radio Observations
  64. Swift-BAT trigger 155764 is not a GRB
  65. Swift-BAT trigger 155764 is probably not a GRB
  66. Swift trigger 155764: bad XRT centroid
  67. Swift-BAT trigger 155535 is definitely not a GRB
  68. GRB050916 : Swift-XRT refined analysis
  69. GRB 050916: XRT position
  70. GRB 050915b, SMARTS optical/IR observations of the XRT position
  71. GRB 050915B: Swift-BAT refined analysis
  72. GRB 050915B: Swift/UVOT Upper Limits
  73. GRB050916: Swift-BAT detection of a long weak burst
  74. GRB 050915a: IR Transient
  75. GRB 050915B: XRT position
  76. GRB 050915b, SMARTS optical/IR observations
  77. GRB050915B: Swift-BAT detection of a long bright burst
  78. GRB050915: Swift/UVOT upper limits
  79. GRB 050915: KAIT optical limit
  80. GRB 050915: IR Observations
  81. GRB 050915: Swift XRT refined analysis
  82. GRB 050915: Swift-BAT refined analysis
  83. GRB050915: P60 Optical Observations
  84. GRB050915, optical observations
  85. GRB050915: XRT position
  86. GRB 050915: ROTSE-III optical limits
  87. GRB 050915: Swift detection of a GRB
  88. GRB050911: Upper limit on X-ray afterglow
  89. Swift-BAT trigger 155072 ground analysis
  90. Swift-BAT trigger 155072 is probably not a GRB
  91. GRB050914: XRT position probably due to cosmic ray
  92. GRB 050911: LCO limits on a variable source
  93. GRB 050908: DEIMOS spectrum and further analysis
  94. Swift is in normal operation
  95. GRB050911: Swift UVOT followup observations
  96. GRB 050911, optical content of Swift/XRT error box
  97. GRB050911: Swift-XRT position
  98. GRB 050911: LCO observations
  99. GRB 050911, optical observations
  100. GRB 050911: Swift-BAT refined analysis

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