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

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