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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 155764 is probably not a GRB
  2. Swift trigger 155764: bad XRT centroid
  3. Swift-BAT trigger 155535 is definitely not a GRB
  4. GRB050916 : Swift-XRT refined analysis
  5. GRB 050916: XRT position
  6. GRB 050915b, SMARTS optical/IR observations of the XRT position
  7. GRB 050915B: Swift-BAT refined analysis
  8. GRB 050915B: Swift/UVOT Upper Limits
  9. GRB050916: Swift-BAT detection of a long weak burst
  10. GRB 050915a: IR Transient
  11. GRB 050915B: XRT position
  12. GRB 050915b, SMARTS optical/IR observations
  13. GRB050915B: Swift-BAT detection of a long bright burst
  14. GRB050915: Swift/UVOT upper limits
  15. GRB 050915: KAIT optical limit
  16. GRB 050915: IR Observations
  17. GRB 050915: Swift XRT refined analysis
  18. GRB 050915: Swift-BAT refined analysis
  19. GRB050915: P60 Optical Observations
  20. GRB050915, optical observations
  21. GRB050915: XRT position
  22. GRB 050915: ROTSE-III optical limits
  23. GRB 050915: Swift detection of a GRB
  24. GRB050911: Upper limit on X-ray afterglow
  25. Swift-BAT trigger 155072 ground analysis
  26. Swift-BAT trigger 155072 is probably not a GRB
  27. GRB050914: XRT position probably due to cosmic ray
  28. GRB 050911: LCO limits on a variable source
  29. GRB 050908: DEIMOS spectrum and further analysis
  30. Swift is in normal operation
  31. GRB050911: Swift UVOT followup observations
  32. GRB 050911, optical content of Swift/XRT error box
  33. GRB050911: Swift-XRT position
  34. GRB 050911: LCO observations
  35. GRB 050911, optical observations
  36. GRB 050911: Swift-BAT refined analysis
  37. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  38. GRB 050911: z~0.16 cluster in the field
  39. GRB050911: Swift-BAT detection of a long burst
  40. GRB050908: detection of Swift/UVOT optical counterpart
  41. GRB 050910a: TAROT early optical limits
  42. RBO GRB 050908 observations
  43. WIRO observations in I of GRB 050908
  44. GRB 050906: Possible X-ray Counterpart
  45. GRB 050906: RTT150 optical observations
  46. GRB050908: Swift/UVOT Early upper limits
  47. GRB050908: VLT R-band decay index.
  48. GRB050908 : Swift-XRT refined analysis
  49. GRB 050908: Swift-BAT refined analysis
  50. GRB 050908: Optical observations
  51. Gemini Spectroscopy of GRB 050908
  52. GRB 050908: spectroscopic redshift
  53. GRB 050908: Prompt PROMPT Observations
  54. GRB 050908 : Swift XRT position
  55. GRB 050908: KAIT observations
  56. GRB 050908: P60 Confirmation of Optical Afterglow
  57. GRB 050908: Optical Observations
  58. GRB 050908: Swift detection of a burst
  59. Swift trigger 154073 is not a GRB
  60. GRB 050906: Optical observations at the Very Large Telescope
  61. GRB050904: CrAO optical observations
  62. GRB 050904 BAT refined analysis of complete data set
  63. GRB 050904: Subaru Optical Spectroscopy
  64. GRB 050906: MARGE Optical Limits
  65. GRB 050906: Swift-BAT refined analysis
  66. GRB 050906: Swift XRT upper limit
  67. GRB 050906: Radio Observations
  68. GRB 050904: Keck I-band Imaging
  69. GRB050906: P60 Observations
  70. GRB 050904: more VLT NIR observations
  71. GRB 050904: BOOTES early R-band observation
  72. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  73. GRB 050906: Bright galaxy in BAT error box
  74. GRB 050906: Swift/BAT Detection of a possible burst
  75. GRB 050904: More SOAR
  76. GRB 050904: photometric redshift
  77. GRB 050904: Swift/UVOT observations
  78. GRB 050904: Afterglow Astrometry
  79. GRB 050904: NIR object inside the XRT error box
  80. GRB 050904: early Swift XRT analysis results
  81. GRB 050904: SOAR YJ and PROMPT Ic Observations
  82. GRB 050904: BAT refined analysis of partial data set
  83. GRB 050904: TAROT optical measurements
  84. GRB050904: Optical Observations
  85. GRB 050904: Environmental Constraints
  86. GRB 050904: Possible High-Redshift GRB
  87. GRB 050904: SOAR/PROMPT Observations
  88. GRB050904: P60 Observations
  89. GRB 050904: TAROT optical limits
  90. GRB050904: Swift-BAT detection of a probable burst
  91. Swift-BAT triggers 153461-153465 are not GRBs
  92. Retraction of Swift-BAT trigger #153355
  93. GRB 050824: MDM Observations
  94. GRB 050827: Swift XRT preliminary analysis results
  95. IBAS Alerts 2641 and 2642: not a real GRB
  96. Swift Trigger #152652 is not a GRB
  97. GRB 050827 : OSN 1.5m optical observations
  98. GRB 050827: P200 NIR Observations
  99. GRB050827: Swift/UVOT upper limits
  100. GRB 050827: Optical Limit

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