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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 051001: Swift-BAT refined analysis
  2. GRB 051001: Swift Detection of a Burst
  3. GRB 051001: ROTSE-III Optical Limits
  4. GRB050908: optical observations
  5. GRB050922C: optical observation
  6. GRB050922B: optical limit
  7. GRB 050922C: further VLT observations
  8. GRB 050820A: NIR photometry at the TNG
  9. GRB050922C: UVES/VLT high resolution spectroscopy
  10. GRB050925: Swift/XRT limits
  11. GRB/SGR 050925: IR Observations
  12. GRB050922C - Swift UVOT preliminary analysis
  13. GRB 050922C: break in the lightcurve
  14. GRB 050925: WSRT Radio Observations
  15. GRB050925: Swift UVOT upper limits
  16. Refined analysis of the Swift-BAT soft short burst
  17. GRB 050925 : I-band observation at Xinglong observatory
  18. GRB050925: Faulkes Telescope North R-band limit
  19. GRB050925: Swift-BAT detection of a short burst
  20. GRB 050922B: Correction to BAT refined analysis, longer burst
  21. GRB050922C: TNG spectroscopic observations
  22. GRB050922B: refined XRT analysis
  23. Konus-Wind observation of GRB 050922C
  24. GRB 050922C: Refined redshift
  25. GRB050922B: Swift UVOT early upper limits.
  26. GRB OT observation
  27. GRB050922C: observation at MonteBoo
  28. INT 2.5m limit for GRB050922B
  29. GRB 050922B: optical limit
  30. GRB050922C: Optical Observations
  31. GRB 050922C: Swift XRT refined analysis
  32. HETE Fregate observations of GRB 050922C
  33. GRB 050922C: Swift-BAT refined analysis
  34. GRB 050922B: Swift-BAT refined analysis
  35. GRB050922C: optical observations
  36. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  37. GRB 050922C: optical obserations
  38. GRB 050922C: NOT optical observations
  39. GRB 050922A: Analysis of Swift/XRT TOO observation
  40. GRB 050922C: Swift detection of a bright burst
  41. GRB 050922C: ROTSE-IIId Refined Analysis
  42. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  43. GRB 050922B: ROTSE-III Optical Limits
  44. GRB 050922B,optical observation
  45. GRB050922B: Swift-BAT detection of a weak long burst
  46. Possible GRB 050922 detected by INTEGRAL
  47. GRB050918: Possible Swift/XRT detected afterglow
  48. GRB050820B: analysis of the XMM-Newton observation
  49. GRB050916: Swift/UVOT Upper Limits
  50. GRB 050916: Swift-BAT refined analysis
  51. GRB 050918 - A long GRB detected by INTEGRAL
  52. GRB 050915a: Radio Observations
  53. Swift-BAT trigger 155764 is not a GRB
  54. Swift-BAT trigger 155764 is probably not a GRB
  55. Swift trigger 155764: bad XRT centroid
  56. Swift-BAT trigger 155535 is definitely not a GRB
  57. GRB050916 : Swift-XRT refined analysis
  58. GRB 050916: XRT position
  59. GRB 050915b, SMARTS optical/IR observations of the XRT position
  60. GRB 050915B: Swift-BAT refined analysis
  61. GRB 050915B: Swift/UVOT Upper Limits
  62. GRB050916: Swift-BAT detection of a long weak burst
  63. GRB 050915a: IR Transient
  64. GRB 050915B: XRT position
  65. GRB 050915b, SMARTS optical/IR observations
  66. GRB050915B: Swift-BAT detection of a long bright burst
  67. GRB050915: Swift/UVOT upper limits
  68. GRB 050915: KAIT optical limit
  69. GRB 050915: IR Observations
  70. GRB 050915: Swift XRT refined analysis
  71. GRB 050915: Swift-BAT refined analysis
  72. GRB050915: P60 Optical Observations
  73. GRB050915, optical observations
  74. GRB050915: XRT position
  75. GRB 050915: ROTSE-III optical limits
  76. GRB 050915: Swift detection of a GRB
  77. GRB050911: Upper limit on X-ray afterglow
  78. Swift-BAT trigger 155072 ground analysis
  79. Swift-BAT trigger 155072 is probably not a GRB
  80. GRB050914: XRT position probably due to cosmic ray
  81. GRB 050911: LCO limits on a variable source
  82. GRB 050908: DEIMOS spectrum and further analysis
  83. Swift is in normal operation
  84. GRB050911: Swift UVOT followup observations
  85. GRB 050911, optical content of Swift/XRT error box
  86. GRB050911: Swift-XRT position
  87. GRB 050911: LCO observations
  88. GRB 050911, optical observations
  89. GRB 050911: Swift-BAT refined analysis
  90. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  91. GRB 050911: z~0.16 cluster in the field
  92. GRB050911: Swift-BAT detection of a long burst
  93. GRB050908: detection of Swift/UVOT optical counterpart
  94. GRB 050910a: TAROT early optical limits
  95. RBO GRB 050908 observations
  96. WIRO observations in I of GRB 050908
  97. GRB 050906: Possible X-ray Counterpart
  98. GRB 050906: RTT150 optical observations
  99. GRB050908: Swift/UVOT Early upper limits
  100. GRB050908: VLT R-band decay index.

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