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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: Refined redshift
  2. GRB050922B: Swift UVOT early upper limits.
  3. GRB OT observation
  4. GRB050922C: observation at MonteBoo
  5. INT 2.5m limit for GRB050922B
  6. GRB 050922B: optical limit
  7. GRB050922C: Optical Observations
  8. GRB 050922C: Swift XRT refined analysis
  9. HETE Fregate observations of GRB 050922C
  10. GRB 050922C: Swift-BAT refined analysis
  11. GRB 050922B: Swift-BAT refined analysis
  12. GRB050922C: optical observations
  13. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  14. GRB 050922C: optical obserations
  15. GRB 050922C: NOT optical observations
  16. GRB 050922A: Analysis of Swift/XRT TOO observation
  17. GRB 050922C: Swift detection of a bright burst
  18. GRB 050922C: ROTSE-IIId Refined Analysis
  19. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  20. GRB 050922B: ROTSE-III Optical Limits
  21. GRB 050922B,optical observation
  22. GRB050922B: Swift-BAT detection of a weak long burst
  23. Possible GRB 050922 detected by INTEGRAL
  24. GRB050918: Possible Swift/XRT detected afterglow
  25. GRB050820B: analysis of the XMM-Newton observation
  26. GRB050916: Swift/UVOT Upper Limits
  27. GRB 050916: Swift-BAT refined analysis
  28. GRB 050918 - A long GRB detected by INTEGRAL
  29. GRB 050915a: Radio Observations
  30. Swift-BAT trigger 155764 is not a GRB
  31. Swift-BAT trigger 155764 is probably not a GRB
  32. Swift trigger 155764: bad XRT centroid
  33. Swift-BAT trigger 155535 is definitely not a GRB
  34. GRB050916 : Swift-XRT refined analysis
  35. GRB 050916: XRT position
  36. GRB 050915b, SMARTS optical/IR observations of the XRT position
  37. GRB 050915B: Swift-BAT refined analysis
  38. GRB 050915B: Swift/UVOT Upper Limits
  39. GRB050916: Swift-BAT detection of a long weak burst
  40. GRB 050915a: IR Transient
  41. GRB 050915B: XRT position
  42. GRB 050915b, SMARTS optical/IR observations
  43. GRB050915B: Swift-BAT detection of a long bright burst
  44. GRB050915: Swift/UVOT upper limits
  45. GRB 050915: KAIT optical limit
  46. GRB 050915: IR Observations
  47. GRB 050915: Swift XRT refined analysis
  48. GRB 050915: Swift-BAT refined analysis
  49. GRB050915: P60 Optical Observations
  50. GRB050915, optical observations
  51. GRB050915: XRT position
  52. GRB 050915: ROTSE-III optical limits
  53. GRB 050915: Swift detection of a GRB
  54. GRB050911: Upper limit on X-ray afterglow
  55. Swift-BAT trigger 155072 ground analysis
  56. Swift-BAT trigger 155072 is probably not a GRB
  57. GRB050914: XRT position probably due to cosmic ray
  58. GRB 050911: LCO limits on a variable source
  59. GRB 050908: DEIMOS spectrum and further analysis
  60. Swift is in normal operation
  61. GRB050911: Swift UVOT followup observations
  62. GRB 050911, optical content of Swift/XRT error box
  63. GRB050911: Swift-XRT position
  64. GRB 050911: LCO observations
  65. GRB 050911, optical observations
  66. GRB 050911: Swift-BAT refined analysis
  67. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  68. GRB 050911: z~0.16 cluster in the field
  69. GRB050911: Swift-BAT detection of a long burst
  70. GRB050908: detection of Swift/UVOT optical counterpart
  71. GRB 050910a: TAROT early optical limits
  72. RBO GRB 050908 observations
  73. WIRO observations in I of GRB 050908
  74. GRB 050906: Possible X-ray Counterpart
  75. GRB 050906: RTT150 optical observations
  76. GRB050908: Swift/UVOT Early upper limits
  77. GRB050908: VLT R-band decay index.
  78. GRB050908 : Swift-XRT refined analysis
  79. GRB 050908: Swift-BAT refined analysis
  80. GRB 050908: Optical observations
  81. Gemini Spectroscopy of GRB 050908
  82. GRB 050908: spectroscopic redshift
  83. GRB 050908: Prompt PROMPT Observations
  84. GRB 050908 : Swift XRT position
  85. GRB 050908: KAIT observations
  86. GRB 050908: P60 Confirmation of Optical Afterglow
  87. GRB 050908: Optical Observations
  88. GRB 050908: Swift detection of a burst
  89. Swift trigger 154073 is not a GRB
  90. GRB 050906: Optical observations at the Very Large Telescope
  91. GRB050904: CrAO optical observations
  92. GRB 050904 BAT refined analysis of complete data set
  93. GRB 050904: Subaru Optical Spectroscopy
  94. GRB 050906: MARGE Optical Limits
  95. GRB 050906: Swift-BAT refined analysis
  96. GRB 050906: Swift XRT upper limit
  97. GRB 050906: Radio Observations
  98. GRB 050904: Keck I-band Imaging
  99. GRB050906: P60 Observations
  100. GRB 050904: more VLT NIR observations

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