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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 050916: Swift-BAT refined analysis
  2. GRB 050918 - A long GRB detected by INTEGRAL
  3. GRB 050915a: Radio Observations
  4. Swift-BAT trigger 155764 is not a GRB
  5. Swift-BAT trigger 155764 is probably not a GRB
  6. Swift trigger 155764: bad XRT centroid
  7. Swift-BAT trigger 155535 is definitely not a GRB
  8. GRB050916 : Swift-XRT refined analysis
  9. GRB 050916: XRT position
  10. GRB 050915b, SMARTS optical/IR observations of the XRT position
  11. GRB 050915B: Swift-BAT refined analysis
  12. GRB 050915B: Swift/UVOT Upper Limits
  13. GRB050916: Swift-BAT detection of a long weak burst
  14. GRB 050915a: IR Transient
  15. GRB 050915B: XRT position
  16. GRB 050915b, SMARTS optical/IR observations
  17. GRB050915B: Swift-BAT detection of a long bright burst
  18. GRB050915: Swift/UVOT upper limits
  19. GRB 050915: KAIT optical limit
  20. GRB 050915: IR Observations
  21. GRB 050915: Swift XRT refined analysis
  22. GRB 050915: Swift-BAT refined analysis
  23. GRB050915: P60 Optical Observations
  24. GRB050915, optical observations
  25. GRB050915: XRT position
  26. GRB 050915: ROTSE-III optical limits
  27. GRB 050915: Swift detection of a GRB
  28. GRB050911: Upper limit on X-ray afterglow
  29. Swift-BAT trigger 155072 ground analysis
  30. Swift-BAT trigger 155072 is probably not a GRB
  31. GRB050914: XRT position probably due to cosmic ray
  32. GRB 050911: LCO limits on a variable source
  33. GRB 050908: DEIMOS spectrum and further analysis
  34. Swift is in normal operation
  35. GRB050911: Swift UVOT followup observations
  36. GRB 050911, optical content of Swift/XRT error box
  37. GRB050911: Swift-XRT position
  38. GRB 050911: LCO observations
  39. GRB 050911, optical observations
  40. GRB 050911: Swift-BAT refined analysis
  41. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  42. GRB 050911: z~0.16 cluster in the field
  43. GRB050911: Swift-BAT detection of a long burst
  44. GRB050908: detection of Swift/UVOT optical counterpart
  45. GRB 050910a: TAROT early optical limits
  46. RBO GRB 050908 observations
  47. WIRO observations in I of GRB 050908
  48. GRB 050906: Possible X-ray Counterpart
  49. GRB 050906: RTT150 optical observations
  50. GRB050908: Swift/UVOT Early upper limits
  51. GRB050908: VLT R-band decay index.
  52. GRB050908 : Swift-XRT refined analysis
  53. GRB 050908: Swift-BAT refined analysis
  54. GRB 050908: Optical observations
  55. Gemini Spectroscopy of GRB 050908
  56. GRB 050908: spectroscopic redshift
  57. GRB 050908: Prompt PROMPT Observations
  58. GRB 050908 : Swift XRT position
  59. GRB 050908: KAIT observations
  60. GRB 050908: P60 Confirmation of Optical Afterglow
  61. GRB 050908: Optical Observations
  62. GRB 050908: Swift detection of a burst
  63. Swift trigger 154073 is not a GRB
  64. GRB 050906: Optical observations at the Very Large Telescope
  65. GRB050904: CrAO optical observations
  66. GRB 050904 BAT refined analysis of complete data set
  67. GRB 050904: Subaru Optical Spectroscopy
  68. GRB 050906: MARGE Optical Limits
  69. GRB 050906: Swift-BAT refined analysis
  70. GRB 050906: Swift XRT upper limit
  71. GRB 050906: Radio Observations
  72. GRB 050904: Keck I-band Imaging
  73. GRB050906: P60 Observations
  74. GRB 050904: more VLT NIR observations
  75. GRB 050904: BOOTES early R-band observation
  76. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  77. GRB 050906: Bright galaxy in BAT error box
  78. GRB 050906: Swift/BAT Detection of a possible burst
  79. GRB 050904: More SOAR
  80. GRB 050904: photometric redshift
  81. GRB 050904: Swift/UVOT observations
  82. GRB 050904: Afterglow Astrometry
  83. GRB 050904: NIR object inside the XRT error box
  84. GRB 050904: early Swift XRT analysis results
  85. GRB 050904: SOAR YJ and PROMPT Ic Observations
  86. GRB 050904: BAT refined analysis of partial data set
  87. GRB 050904: TAROT optical measurements
  88. GRB050904: Optical Observations
  89. GRB 050904: Environmental Constraints
  90. GRB 050904: Possible High-Redshift GRB
  91. GRB 050904: SOAR/PROMPT Observations
  92. GRB050904: P60 Observations
  93. GRB 050904: TAROT optical limits
  94. GRB050904: Swift-BAT detection of a probable burst
  95. Swift-BAT triggers 153461-153465 are not GRBs
  96. Retraction of Swift-BAT trigger #153355
  97. GRB 050824: MDM Observations
  98. GRB 050827: Swift XRT preliminary analysis results
  99. IBAS Alerts 2641 and 2642: not a real GRB
  100. Swift Trigger #152652 is not a GRB

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