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

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