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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. GRB050915, optical observations
  2. GRB050915: XRT position
  3. GRB 050915: ROTSE-III optical limits
  4. GRB 050915: Swift detection of a GRB
  5. GRB050911: Upper limit on X-ray afterglow
  6. Swift-BAT trigger 155072 ground analysis
  7. Swift-BAT trigger 155072 is probably not a GRB
  8. GRB050914: XRT position probably due to cosmic ray
  9. GRB 050911: LCO limits on a variable source
  10. GRB 050908: DEIMOS spectrum and further analysis
  11. Swift is in normal operation
  12. GRB050911: Swift UVOT followup observations
  13. GRB 050911, optical content of Swift/XRT error box
  14. GRB050911: Swift-XRT position
  15. GRB 050911: LCO observations
  16. GRB 050911, optical observations
  17. GRB 050911: Swift-BAT refined analysis
  18. Later Swift-BAT triggers 154632 and 154633 RETRACTION
  19. GRB 050911: z~0.16 cluster in the field
  20. GRB050911: Swift-BAT detection of a long burst
  21. GRB050908: detection of Swift/UVOT optical counterpart
  22. GRB 050910a: TAROT early optical limits
  23. RBO GRB 050908 observations
  24. WIRO observations in I of GRB 050908
  25. GRB 050906: Possible X-ray Counterpart
  26. GRB 050906: RTT150 optical observations
  27. GRB050908: Swift/UVOT Early upper limits
  28. GRB050908: VLT R-band decay index.
  29. GRB050908 : Swift-XRT refined analysis
  30. GRB 050908: Swift-BAT refined analysis
  31. GRB 050908: Optical observations
  32. Gemini Spectroscopy of GRB 050908
  33. GRB 050908: spectroscopic redshift
  34. GRB 050908: Prompt PROMPT Observations
  35. GRB 050908 : Swift XRT position
  36. GRB 050908: KAIT observations
  37. GRB 050908: P60 Confirmation of Optical Afterglow
  38. GRB 050908: Optical Observations
  39. GRB 050908: Swift detection of a burst
  40. Swift trigger 154073 is not a GRB
  41. GRB 050906: Optical observations at the Very Large Telescope
  42. GRB050904: CrAO optical observations
  43. GRB 050904 BAT refined analysis of complete data set
  44. GRB 050904: Subaru Optical Spectroscopy
  45. GRB 050906: MARGE Optical Limits
  46. GRB 050906: Swift-BAT refined analysis
  47. GRB 050906: Swift XRT upper limit
  48. GRB 050906: Radio Observations
  49. GRB 050904: Keck I-band Imaging
  50. GRB050906: P60 Observations
  51. GRB 050904: more VLT NIR observations
  52. GRB 050904: BOOTES early R-band observation
  53. GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
  54. GRB 050906: Bright galaxy in BAT error box
  55. GRB 050906: Swift/BAT Detection of a possible burst
  56. GRB 050904: More SOAR
  57. GRB 050904: photometric redshift
  58. GRB 050904: Swift/UVOT observations
  59. GRB 050904: Afterglow Astrometry
  60. GRB 050904: NIR object inside the XRT error box
  61. GRB 050904: early Swift XRT analysis results
  62. GRB 050904: SOAR YJ and PROMPT Ic Observations
  63. GRB 050904: BAT refined analysis of partial data set
  64. GRB 050904: TAROT optical measurements
  65. GRB050904: Optical Observations
  66. GRB 050904: Environmental Constraints
  67. GRB 050904: Possible High-Redshift GRB
  68. GRB 050904: SOAR/PROMPT Observations
  69. GRB050904: P60 Observations
  70. GRB 050904: TAROT optical limits
  71. GRB050904: Swift-BAT detection of a probable burst
  72. Swift-BAT triggers 153461-153465 are not GRBs
  73. Retraction of Swift-BAT trigger #153355
  74. GRB 050824: MDM Observations
  75. GRB 050827: Swift XRT preliminary analysis results
  76. IBAS Alerts 2641 and 2642: not a real GRB
  77. Swift Trigger #152652 is not a GRB
  78. GRB 050827 : OSN 1.5m optical observations
  79. GRB 050827: P200 NIR Observations
  80. GRB050827: Swift/UVOT upper limits
  81. GRB 050827: Optical Limit
  82. GRB 050827: XRT possible afterglow detection
  83. GRB 050826 : Lulin R band observation
  84. GRB050824: Maidanak optical limits
  85. GRB050820A: RTT150 optical observations
  86. GRB050827: RTT150 optical observations
  87. GRB 050827: Swift-BAT refined analysis
  88. GRB050827: Swift-BAT detection of a burst
  89. Subaru Observations of GRB050724
  90. GRB 050826: Optical Candidate
  91. GRB050824, HETE-2 Observation
  92. GRB 050826: Swift XRT preliminary analysis results
  93. GRB 050826: BAT refined analysis
  94. GRB050826: Swift/UVOT early upper limits
  95. GRB050824: First 2 hours of power low optical decay?
  96. GRB 050826: Swift XRT position
  97. GRB050826: Swift-BAT detection of a long burst
  98. GRB050824: MASTER final analysis of the OT observations
  99. Possible GRB050825:MASTER optical observations
  100. Swift-BAT trigger 152038 is definitely not a GRB

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