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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. GRB 050925: Second Epoch WSRT Radio Observations
  2. GRB 051001: Swift XRT refined analysis
  3. GRB 051001, optical observations at Mt. John
  4. GRB 051001: I-band limit
  5. GRB 051001: AAT infra-red observations
  6. GRB 051001: Swift-BAT refined analysis
  7. GRB 051001: Swift Detection of a Burst
  8. GRB 051001: ROTSE-III Optical Limits
  9. GRB050908: optical observations
  10. GRB050922C: optical observation
  11. GRB050922B: optical limit
  12. GRB 050922C: further VLT observations
  13. GRB 050820A: NIR photometry at the TNG
  14. GRB050922C: UVES/VLT high resolution spectroscopy
  15. GRB050925: Swift/XRT limits
  16. GRB/SGR 050925: IR Observations
  17. GRB050922C - Swift UVOT preliminary analysis
  18. GRB 050922C: break in the lightcurve
  19. GRB 050925: WSRT Radio Observations
  20. GRB050925: Swift UVOT upper limits
  21. Refined analysis of the Swift-BAT soft short burst
  22. GRB 050925 : I-band observation at Xinglong observatory
  23. GRB050925: Faulkes Telescope North R-band limit
  24. GRB050925: Swift-BAT detection of a short burst
  25. GRB 050922B: Correction to BAT refined analysis, longer burst
  26. GRB050922C: TNG spectroscopic observations
  27. GRB050922B: refined XRT analysis
  28. Konus-Wind observation of GRB 050922C
  29. GRB 050922C: Refined redshift
  30. GRB050922B: Swift UVOT early upper limits.
  31. GRB OT observation
  32. GRB050922C: observation at MonteBoo
  33. INT 2.5m limit for GRB050922B
  34. GRB 050922B: optical limit
  35. GRB050922C: Optical Observations
  36. GRB 050922C: Swift XRT refined analysis
  37. HETE Fregate observations of GRB 050922C
  38. GRB 050922C: Swift-BAT refined analysis
  39. GRB 050922B: Swift-BAT refined analysis
  40. GRB050922C: optical observations
  41. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  42. GRB 050922C: optical obserations
  43. GRB 050922C: NOT optical observations
  44. GRB 050922A: Analysis of Swift/XRT TOO observation
  45. GRB 050922C: Swift detection of a bright burst
  46. GRB 050922C: ROTSE-IIId Refined Analysis
  47. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  48. GRB 050922B: ROTSE-III Optical Limits
  49. GRB 050922B,optical observation
  50. GRB050922B: Swift-BAT detection of a weak long burst
  51. Possible GRB 050922 detected by INTEGRAL
  52. GRB050918: Possible Swift/XRT detected afterglow
  53. GRB050820B: analysis of the XMM-Newton observation
  54. GRB050916: Swift/UVOT Upper Limits
  55. GRB 050916: Swift-BAT refined analysis
  56. GRB 050918 - A long GRB detected by INTEGRAL
  57. GRB 050915a: Radio Observations
  58. Swift-BAT trigger 155764 is not a GRB
  59. Swift-BAT trigger 155764 is probably not a GRB
  60. Swift trigger 155764: bad XRT centroid
  61. Swift-BAT trigger 155535 is definitely not a GRB
  62. GRB050916 : Swift-XRT refined analysis
  63. GRB 050916: XRT position
  64. GRB 050915b, SMARTS optical/IR observations of the XRT position
  65. GRB 050915B: Swift-BAT refined analysis
  66. GRB 050915B: Swift/UVOT Upper Limits
  67. GRB050916: Swift-BAT detection of a long weak burst
  68. GRB 050915a: IR Transient
  69. GRB 050915B: XRT position
  70. GRB 050915b, SMARTS optical/IR observations
  71. GRB050915B: Swift-BAT detection of a long bright burst
  72. GRB050915: Swift/UVOT upper limits
  73. GRB 050915: KAIT optical limit
  74. GRB 050915: IR Observations
  75. GRB 050915: Swift XRT refined analysis
  76. GRB 050915: Swift-BAT refined analysis
  77. GRB050915: P60 Optical Observations
  78. GRB050915, optical observations
  79. GRB050915: XRT position
  80. GRB 050915: ROTSE-III optical limits
  81. GRB 050915: Swift detection of a GRB
  82. GRB050911: Upper limit on X-ray afterglow
  83. Swift-BAT trigger 155072 ground analysis
  84. Swift-BAT trigger 155072 is probably not a GRB
  85. GRB050914: XRT position probably due to cosmic ray
  86. GRB 050911: LCO limits on a variable source
  87. GRB 050908: DEIMOS spectrum and further analysis
  88. Swift is in normal operation
  89. GRB050911: Swift UVOT followup observations
  90. GRB 050911, optical content of Swift/XRT error box
  91. GRB050911: Swift-XRT position
  92. GRB 050911: LCO observations
  93. GRB 050911, optical observations
  94. GRB 050911: Swift-BAT refined analysis
  95. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  96. GRB 050911: z~0.16 cluster in the field
  97. GRB050911: Swift-BAT detection of a long burst
  98. GRB050908: detection of Swift/UVOT optical counterpart
  99. GRB 050910a: TAROT early optical limits
  100. RBO GRB 050908 observations

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