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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 051006: XRT position
  2. GRB051006: Swift detection of a burst
  3. GRB 050906, summary of radio observations
  4. Swift-BAT triggers 158261 and 158262 Retraction
  5. GRB051001: Swift UVOT Upper Limits
  6. GRB 050925: Second Epoch WSRT Radio Observations
  7. GRB 051001: Swift XRT refined analysis
  8. GRB 051001, optical observations at Mt. John
  9. GRB 051001: I-band limit
  10. GRB 051001: AAT infra-red observations
  11. GRB 051001: Swift-BAT refined analysis
  12. GRB 051001: Swift Detection of a Burst
  13. GRB 051001: ROTSE-III Optical Limits
  14. GRB050908: optical observations
  15. GRB050922C: optical observation
  16. GRB050922B: optical limit
  17. GRB 050922C: further VLT observations
  18. GRB 050820A: NIR photometry at the TNG
  19. GRB050922C: UVES/VLT high resolution spectroscopy
  20. GRB050925: Swift/XRT limits
  21. GRB/SGR 050925: IR Observations
  22. GRB050922C - Swift UVOT preliminary analysis
  23. GRB 050922C: break in the lightcurve
  24. GRB 050925: WSRT Radio Observations
  25. GRB050925: Swift UVOT upper limits
  26. Refined analysis of the Swift-BAT soft short burst
  27. GRB 050925 : I-band observation at Xinglong observatory
  28. GRB050925: Faulkes Telescope North R-band limit
  29. GRB050925: Swift-BAT detection of a short burst
  30. GRB 050922B: Correction to BAT refined analysis, longer burst
  31. GRB050922C: TNG spectroscopic observations
  32. GRB050922B: refined XRT analysis
  33. Konus-Wind observation of GRB 050922C
  34. GRB 050922C: Refined redshift
  35. GRB050922B: Swift UVOT early upper limits.
  36. GRB OT observation
  37. GRB050922C: observation at MonteBoo
  38. INT 2.5m limit for GRB050922B
  39. GRB 050922B: optical limit
  40. GRB050922C: Optical Observations
  41. GRB 050922C: Swift XRT refined analysis
  42. HETE Fregate observations of GRB 050922C
  43. GRB 050922C: Swift-BAT refined analysis
  44. GRB 050922B: Swift-BAT refined analysis
  45. GRB050922C: optical observations
  46. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  47. GRB 050922C: optical obserations
  48. GRB 050922C: NOT optical observations
  49. GRB 050922A: Analysis of Swift/XRT TOO observation
  50. GRB 050922C: Swift detection of a bright burst
  51. GRB 050922C: ROTSE-IIId Refined Analysis
  52. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  53. GRB 050922B: ROTSE-III Optical Limits
  54. GRB 050922B,optical observation
  55. GRB050922B: Swift-BAT detection of a weak long burst
  56. Possible GRB 050922 detected by INTEGRAL
  57. GRB050918: Possible Swift/XRT detected afterglow
  58. GRB050820B: analysis of the XMM-Newton observation
  59. GRB050916: Swift/UVOT Upper Limits
  60. GRB 050916: Swift-BAT refined analysis
  61. GRB 050918 - A long GRB detected by INTEGRAL
  62. GRB 050915a: Radio Observations
  63. Swift-BAT trigger 155764 is not a GRB
  64. Swift-BAT trigger 155764 is probably not a GRB
  65. Swift trigger 155764: bad XRT centroid
  66. Swift-BAT trigger 155535 is definitely not a GRB
  67. GRB050916 : Swift-XRT refined analysis
  68. GRB 050916: XRT position
  69. GRB 050915b, SMARTS optical/IR observations of the XRT position
  70. GRB 050915B: Swift-BAT refined analysis
  71. GRB 050915B: Swift/UVOT Upper Limits
  72. GRB050916: Swift-BAT detection of a long weak burst
  73. GRB 050915a: IR Transient
  74. GRB 050915B: XRT position
  75. GRB 050915b, SMARTS optical/IR observations
  76. GRB050915B: Swift-BAT detection of a long bright burst
  77. GRB050915: Swift/UVOT upper limits
  78. GRB 050915: KAIT optical limit
  79. GRB 050915: IR Observations
  80. GRB 050915: Swift XRT refined analysis
  81. GRB 050915: Swift-BAT refined analysis
  82. GRB050915: P60 Optical Observations
  83. GRB050915, optical observations
  84. GRB050915: XRT position
  85. GRB 050915: ROTSE-III optical limits
  86. GRB 050915: Swift detection of a GRB
  87. GRB050911: Upper limit on X-ray afterglow
  88. Swift-BAT trigger 155072 ground analysis
  89. Swift-BAT trigger 155072 is probably not a GRB
  90. GRB050914: XRT position probably due to cosmic ray
  91. GRB 050911: LCO limits on a variable source
  92. GRB 050908: DEIMOS spectrum and further analysis
  93. Swift is in normal operation
  94. GRB050911: Swift UVOT followup observations
  95. GRB 050911, optical content of Swift/XRT error box
  96. GRB050911: Swift-XRT position
  97. GRB 050911: LCO observations
  98. GRB 050911, optical observations
  99. GRB 050911: Swift-BAT refined analysis
  100. Later Swift-BAT triggers 154632 and 154633 RETRACTION

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