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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. Swift-BAT trigger 155535 is definitely not a GRB
  2. GRB050916 : Swift-XRT refined analysis
  3. GRB 050916: XRT position
  4. GRB 050915b, SMARTS optical/IR observations of the XRT position
  5. GRB 050915B: Swift-BAT refined analysis
  6. GRB 050915B: Swift/UVOT Upper Limits
  7. GRB050916: Swift-BAT detection of a long weak burst
  8. GRB 050915a: IR Transient
  9. GRB 050915B: XRT position
  10. GRB 050915b, SMARTS optical/IR observations
  11. GRB050915B: Swift-BAT detection of a long bright burst
  12. GRB050915: Swift/UVOT upper limits
  13. GRB 050915: KAIT optical limit
  14. GRB 050915: IR Observations
  15. GRB 050915: Swift XRT refined analysis
  16. GRB 050915: Swift-BAT refined analysis
  17. GRB050915: P60 Optical Observations
  18. GRB050915, optical observations
  19. GRB050915: XRT position
  20. GRB 050915: ROTSE-III optical limits
  21. GRB 050915: Swift detection of a GRB
  22. GRB050911: Upper limit on X-ray afterglow
  23. Swift-BAT trigger 155072 ground analysis
  24. Swift-BAT trigger 155072 is probably not a GRB
  25. GRB050914: XRT position probably due to cosmic ray
  26. GRB 050911: LCO limits on a variable source
  27. GRB 050908: DEIMOS spectrum and further analysis
  28. Swift is in normal operation
  29. GRB050911: Swift UVOT followup observations
  30. GRB 050911, optical content of Swift/XRT error box
  31. GRB050911: Swift-XRT position
  32. GRB 050911: LCO observations
  33. GRB 050911, optical observations
  34. GRB 050911: Swift-BAT refined analysis
  35. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  36. GRB 050911: z~0.16 cluster in the field
  37. GRB050911: Swift-BAT detection of a long burst
  38. GRB050908: detection of Swift/UVOT optical counterpart
  39. GRB 050910a: TAROT early optical limits
  40. RBO GRB 050908 observations
  41. WIRO observations in I of GRB 050908
  42. GRB 050906: Possible X-ray Counterpart
  43. GRB 050906: RTT150 optical observations
  44. GRB050908: Swift/UVOT Early upper limits
  45. GRB050908: VLT R-band decay index.
  46. GRB050908 : Swift-XRT refined analysis
  47. GRB 050908: Swift-BAT refined analysis
  48. GRB 050908: Optical observations
  49. Gemini Spectroscopy of GRB 050908
  50. GRB 050908: spectroscopic redshift
  51. GRB 050908: Prompt PROMPT Observations
  52. GRB 050908 : Swift XRT position
  53. GRB 050908: KAIT observations
  54. GRB 050908: P60 Confirmation of Optical Afterglow
  55. GRB 050908: Optical Observations
  56. GRB 050908: Swift detection of a burst
  57. Swift trigger 154073 is not a GRB
  58. GRB 050906: Optical observations at the Very Large Telescope
  59. GRB050904: CrAO optical observations
  60. GRB 050904 BAT refined analysis of complete data set
  61. GRB 050904: Subaru Optical Spectroscopy
  62. GRB 050906: MARGE Optical Limits
  63. GRB 050906: Swift-BAT refined analysis
  64. GRB 050906: Swift XRT upper limit
  65. GRB 050906: Radio Observations
  66. GRB 050904: Keck I-band Imaging
  67. GRB050906: P60 Observations
  68. GRB 050904: more VLT NIR observations
  69. GRB 050904: BOOTES early R-band observation
  70. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  71. GRB 050906: Bright galaxy in BAT error box
  72. GRB 050906: Swift/BAT Detection of a possible burst
  73. GRB 050904: More SOAR
  74. GRB 050904: photometric redshift
  75. GRB 050904: Swift/UVOT observations
  76. GRB 050904: Afterglow Astrometry
  77. GRB 050904: NIR object inside the XRT error box
  78. GRB 050904: early Swift XRT analysis results
  79. GRB 050904: SOAR YJ and PROMPT Ic Observations
  80. GRB 050904: BAT refined analysis of partial data set
  81. GRB 050904: TAROT optical measurements
  82. GRB050904: Optical Observations
  83. GRB 050904: Environmental Constraints
  84. GRB 050904: Possible High-Redshift GRB
  85. GRB 050904: SOAR/PROMPT Observations
  86. GRB050904: P60 Observations
  87. GRB 050904: TAROT optical limits
  88. GRB050904: Swift-BAT detection of a probable burst
  89. Swift-BAT triggers 153461-153465 are not GRBs
  90. Retraction of Swift-BAT trigger #153355
  91. GRB 050824: MDM Observations
  92. GRB 050827: Swift XRT preliminary analysis results
  93. IBAS Alerts 2641 and 2642: not a real GRB
  94. Swift Trigger #152652 is not a GRB
  95. GRB 050827 : OSN 1.5m optical observations
  96. GRB 050827: P200 NIR Observations
  97. GRB050827: Swift/UVOT upper limits
  98. GRB 050827: Optical Limit
  99. GRB 050827: XRT possible afterglow detection
  100. GRB 050826 : Lulin R band observation

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