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

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