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

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