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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"

25904 results found.

  1. GRB 050922B: Correction to BAT refined analysis, longer burst
  2. GRB050922C: TNG spectroscopic observations
  3. GRB050922B: refined XRT analysis
  4. Konus-Wind observation of GRB 050922C
  5. GRB050922B: Swift UVOT early upper limits.
  6. INT 2.5m limit for GRB050922B
  7. GRB 050922B: optical limit
  8. GRB 050922C: Swift XRT refined analysis
  9. HETE Fregate observations of GRB 050922C
  10. GRB 050922C: Swift-BAT refined analysis
  11. GRB 050922B: Swift-BAT refined analysis
  12. GRB050922C: optical observations
  13. GRB 050922C: Absorption redshift from the Nordic Optical Telescope
  14. GRB 050922C: optical obserations
  15. GRB 050922C: NOT optical observations
  16. GRB 050922A: Analysis of Swift/XRT TOO observation
  17. GRB 050922C: Swift detection of a bright burst
  18. GRB 050922C: ROTSE-IIId Refined Analysis
  19. GRB 050922C: ROTSE-III Detection of Possible Counterpart
  20. GRB 050922B: ROTSE-III Optical Limits
  21. GRB 050922B,optical observation
  22. GRB050922B: Swift-BAT detection of a weak long burst
  23. GRB050918: Possible Swift/XRT detected afterglow
  24. GRB050820B: analysis of the XMM-Newton observation
  25. GRB050916: Swift/UVOT Upper Limits
  26. GRB 050916: Swift-BAT refined analysis
  27. GRB 050915a: Radio Observations
  28. Swift-BAT trigger 155764 is not a GRB
  29. Swift-BAT trigger 155764 is probably not a GRB
  30. Swift trigger 155764: bad XRT centroid
  31. Swift-BAT trigger 155535 is definitely not a GRB
  32. GRB050916 : Swift-XRT refined analysis
  33. GRB 050916: XRT position
  34. GRB 050915b, SMARTS optical/IR observations of the XRT position
  35. GRB 050915B: Swift-BAT refined analysis
  36. GRB 050915B: Swift/UVOT Upper Limits
  37. GRB050916: Swift-BAT detection of a long weak burst
  38. GRB 050915a: IR Transient
  39. GRB 050915B: XRT position
  40. GRB050915B: Swift-BAT detection of a long bright burst
  41. GRB050915: Swift/UVOT upper limits
  42. GRB 050915: KAIT optical limit
  43. GRB 050915: IR Observations
  44. GRB 050915: Swift XRT refined analysis
  45. GRB 050915: Swift-BAT refined analysis
  46. GRB050915: P60 Optical Observations
  47. GRB050915, optical observations
  48. GRB050915: XRT position
  49. GRB 050915: ROTSE-III optical limits
  50. GRB 050915: Swift detection of a GRB
  51. GRB050911: Upper limit on X-ray afterglow
  52. Swift-BAT trigger 155072 ground analysis
  53. Swift-BAT trigger 155072 is probably not a GRB
  54. GRB050914: XRT position probably due to cosmic ray
  55. GRB 050911: LCO limits on a variable source
  56. GRB 050908: DEIMOS spectrum and further analysis
  57. Swift is in normal operation
  58. GRB050911: Swift UVOT followup observations
  59. GRB 050911, optical content of Swift/XRT error box
  60. GRB050911: Swift-XRT position
  61. GRB 050911, optical observations
  62. GRB 050911: Swift-BAT refined analysis
  63. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  64. GRB050911: Swift-BAT detection of a long burst
  65. GRB050908: detection of Swift/UVOT optical counterpart
  66. GRB 050910a: TAROT early optical limits
  67. RBO GRB 050908 observations
  68. WIRO observations in I of GRB 050908
  69. GRB 050906: Possible X-ray Counterpart
  70. GRB050908: Swift/UVOT Early upper limits
  71. GRB050908: VLT R-band decay index.
  72. GRB050908 : Swift-XRT refined analysis
  73. GRB 050908: Swift-BAT refined analysis
  74. GRB 050908: Optical observations
  75. Gemini Spectroscopy of GRB 050908
  76. GRB 050908: spectroscopic redshift
  77. GRB 050908: Prompt PROMPT Observations
  78. GRB 050908 : Swift XRT position
  79. GRB 050908: KAIT observations
  80. GRB 050908: P60 Confirmation of Optical Afterglow
  81. GRB 050908: Swift detection of a burst
  82. Swift trigger 154073 is not a GRB
  83. GRB050904: CrAO optical observations
  84. GRB 050904 BAT refined analysis of complete data set
  85. GRB 050904: Subaru Optical Spectroscopy
  86. GRB 050906: MARGE Optical Limits
  87. GRB 050906: Swift-BAT refined analysis
  88. GRB 050906: Swift XRT upper limit
  89. GRB 050904: Keck I-band Imaging
  90. GRB050906: P60 Observations
  91. GRB 050904: more VLT NIR observations
  92. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  93. GRB 050906: Bright galaxy in BAT error box
  94. GRB 050906: Swift/BAT Detection of a possible burst
  95. GRB 050904: More SOAR
  96. GRB 050904: photometric redshift
  97. GRB 050904: Swift/UVOT observations
  98. GRB 050904: Afterglow Astrometry
  99. GRB 050904: NIR object inside the XRT error box
  100. GRB 050904: early Swift XRT analysis results

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