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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: P60 Observations
  2. grb test
  3. GRB 051006: XRT refined analysis
  4. Swift-BAT trigger 158700 is a probable Cosmic Ray Shower Event
  5. GRB 051006: optical observations at Sierra Nevada
  6. GRB051006: Refined analysis of the Swift-BAT burst
  7. GRB 051006: XRT position
  8. GRB051006: Swift detection of a burst
  9. GRB 050906, summary of radio observations
  10. Swift-BAT triggers 158261 and 158262 Retraction
  11. GRB051001: Swift UVOT Upper Limits
  12. GRB 050925: Second Epoch WSRT Radio Observations
  13. GRB 051001: Swift XRT refined analysis
  14. GRB 051001, optical observations at Mt. John
  15. GRB 051001: I-band limit
  16. GRB 051001: AAT infra-red observations
  17. GRB 051001: Swift-BAT refined analysis
  18. GRB 051001: Swift Detection of a Burst
  19. GRB 051001: ROTSE-III Optical Limits
  20. GRB050908: optical observations
  21. GRB050922C: optical observation
  22. GRB050922B: optical limit
  23. GRB 050922C: further VLT observations
  24. GRB 050820A: NIR photometry at the TNG
  25. GRB050922C: UVES/VLT high resolution spectroscopy
  26. GRB050925: Swift/XRT limits
  27. GRB/SGR 050925: IR Observations
  28. GRB050922C - Swift UVOT preliminary analysis
  29. GRB 050922C: break in the lightcurve
  30. GRB 050925: WSRT Radio Observations
  31. GRB050925: Swift UVOT upper limits
  32. Refined analysis of the Swift-BAT soft short burst
  33. GRB 050925 : I-band observation at Xinglong observatory
  34. GRB050925: Faulkes Telescope North R-band limit
  35. GRB050925: Swift-BAT detection of a short burst
  36. GRB 050922B: Correction to BAT refined analysis, longer burst
  37. GRB050922C: TNG spectroscopic observations
  38. GRB050922B: refined XRT analysis
  39. Konus-Wind observation of GRB 050922C
  40. GRB 050922C: Refined redshift
  41. GRB050922B: Swift UVOT early upper limits.
  42. GRB OT observation
  43. GRB050922C: observation at MonteBoo
  44. INT 2.5m limit for GRB050922B
  45. GRB 050922B: optical limit
  46. GRB050922C: Optical Observations
  47. GRB 050922C: Swift XRT refined analysis
  48. HETE Fregate observations of GRB 050922C
  49. GRB 050922C: Swift-BAT refined analysis
  50. GRB 050922B: Swift-BAT refined analysis
  51. GRB050922C: optical observations
  52. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  53. GRB 050922C: optical obserations
  54. GRB 050922C: NOT optical observations
  55. GRB 050922A: Analysis of Swift/XRT TOO observation
  56. GRB 050922C: Swift detection of a bright burst
  57. GRB 050922C: ROTSE-IIId Refined Analysis
  58. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  59. GRB 050922B: ROTSE-III Optical Limits
  60. GRB 050922B,optical observation
  61. GRB050922B: Swift-BAT detection of a weak long burst
  62. Possible GRB 050922 detected by INTEGRAL
  63. GRB050918: Possible Swift/XRT detected afterglow
  64. GRB050820B: analysis of the XMM-Newton observation
  65. GRB050916: Swift/UVOT Upper Limits
  66. GRB 050916: Swift-BAT refined analysis
  67. GRB 050918 - A long GRB detected by INTEGRAL
  68. GRB 050915a: Radio Observations
  69. Swift-BAT trigger 155764 is not a GRB
  70. Swift-BAT trigger 155764 is probably not a GRB
  71. Swift trigger 155764: bad XRT centroid
  72. Swift-BAT trigger 155535 is definitely not a GRB
  73. GRB050916 : Swift-XRT refined analysis
  74. GRB 050916: XRT position
  75. GRB 050915b, SMARTS optical/IR observations of the XRT position
  76. GRB 050915B: Swift-BAT refined analysis
  77. GRB 050915B: Swift/UVOT Upper Limits
  78. GRB050916: Swift-BAT detection of a long weak burst
  79. GRB 050915a: IR Transient
  80. GRB 050915B: XRT position
  81. GRB 050915b, SMARTS optical/IR observations
  82. GRB050915B: Swift-BAT detection of a long bright burst
  83. GRB050915: Swift/UVOT upper limits
  84. GRB 050915: KAIT optical limit
  85. GRB 050915: IR Observations
  86. GRB 050915: Swift XRT refined analysis
  87. GRB 050915: Swift-BAT refined analysis
  88. GRB050915: P60 Optical Observations
  89. GRB050915, optical observations
  90. GRB050915: XRT position
  91. GRB 050915: ROTSE-III optical limits
  92. GRB 050915: Swift detection of a GRB
  93. GRB050911: Upper limit on X-ray afterglow
  94. Swift-BAT trigger 155072 ground analysis
  95. Swift-BAT trigger 155072 is probably not a GRB
  96. GRB050914: XRT position probably due to cosmic ray
  97. GRB 050911: LCO limits on a variable source
  98. GRB 050908: DEIMOS spectrum and further analysis
  99. Swift is in normal operation
  100. GRB050911: Swift UVOT followup observations

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