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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. Fermi LAT/GBM short-hard GRB 081024B: Possible TLS Afterglow
  2. GRB 081028: Swift detection of a burst
  3. GRB 081025: TLS upper limits
  4. GRB 081024: No radio detection with the VLA
  5. GRB081025: RTT150 optical observations
  6. GRB081024B: P200 Observations
  7. GRB 081024B: Swift-XRT further observations
  8. GRB 081025 BAT refined analysis
  9. Swift UVOT observations of GRB081025
  10. Swift UVOT observations of GRB081024B
  11. Konus-Wind observation of GRB 081025
  12. GRB 081025: Swift-XRT position
  13. GRB 081024B: Swift-XRT observations
  14. GRB 081025: Burst detection from Swift-BAT slew data
  15. GRB 081024B: Fermi Gamma-ray Burst Monitor detection
  16. Fermi-LAT observation of GRB 081024B
  17. Swift UVOT observations of GRB 081024
  18. GRB 081024: Swift-XRT refined analysis
  19. GRB 081024, Swift-BAT refined analysis
  20. GRB 081024: Enhanced Swift-XRT position
  21. GRB 081024: Faulkes Telescope North optical observations
  22. GRB 081024: KAIT Optical Limits
  23. GRB 081024: Early Super-LOTIS Observations
  24. GRB 081024A: ROTSE-III Optical Limits
  25. GRB 081024: Swift detection of a burst
  26. GRB 081022, Swift-BAT refined analysis
  27. GRB 081016A: Swift-XRT refined analysis
  28. GRB 081022: Swift detection of a burst
  29. GRB 081012: Swift-XRT Refined Analysis
  30. Swift trigger 332287 is not a GRB
  31. Swift detection of a possible burst (trigger 332287)
  32. GRB 081012 - Enhanced Swift XRT position
  33. GRB 081017, Swift-BAT refined analysis
  34. GRB 081017: REM early observations
  35. GRB 081017: Swift detection of a burst
  36. GRB 081016B, Swift-BAT refined analysis
  37. GRB 081016B: Swift/UVOT Upper Limits
  38. GRB 081011: Swift XRT refined analysis
  39. GRB 081016B: Swift-XRT Team refined Analysis
  40. GRB 081016B: Enhanced Swift-XRT position
  41. GRB 081016B: ROTSE-III Optical Limits
  42. GRB 081016B: Swift detection of a burst
  43. GRB 081011: Enhanced Swift-XRT position
  44. GRB 081016: Swift-XRT candidate afterglow detection
  45. Swift detection of flare on CC Eri
  46. GRB 081016: A long GRB discovered by INTEGRAL
  47. Trigger 331721 Due to Swift startracker loss-of-lock
  48. Detection of flare star Algol in Swift-BAT slew data
  49. GRB 081009: Fermi GBM detection
  50. GRB 081012: GROND upper limits
  51. GRB 081008: Galaxy associated with z=1.967 absorber
  52. Swift-BAT triggered on the flare star Algol
  53. GRB 081012: Fermi GBM detection
  54. GRB 081007 and GRB 081007B: Fermi GBM detection
  55. GRB 080430: optical observations
  56. GRB 081008 optical upper limit
  57. GRB 081012: Observations from NOT
  58. GRB 081012: Swift/UVOT analysis of initial observations
  59. GRB 081012: Swift/XRT detection
  60. GRB 081012, Swift-BAT refined analysis
  61. GRB 081012: ROTSE-III Optical Limits
  62. GRB 081012: Swift detection of a burst
  63. Revised table for GRB 081011 UVOT detections
  64. GRB081011: UVOT detection of an optical afterglow
  65. GRB 081011: Swift/XRT detection
  66. GRB 081011, Swift-BAT refined analysis
  67. GRB 081008, SMARTS optical/IR afterglow observations
  68. GRB 081011: Swift detection of a burst
  69. GRB 081007: Radio Detection
  70. Konus-Wind observation of GRB 081001
  71. GRB 081007: Rapid PROMPT Detections
  72. GRB 081008, Swift-BAT refined analysis
  73. GRB 081008: VLT redshift confirmation
  74. GRB 081008: Swift-XRT Refined Analysis
  75. GRB081008: Swift/UVOT observations
  76. GRB 081008: Enhanced Swift-XRT position
  77. GRB 081008: Gemini-South Absorption Redshiftt
  78. GRB 081008: VLT/FORS2 spectroscopy
  79. GRB 081008: Swift detection of a burst with optical afterglow
  80. GRB 081008: ROTSE-III Detection of Optical Counterpart
  81. GRB081006B: Fermi GBM detection
  82. GRB081006: Fermi GBM detection
  83. GRB081007: Swift/UVOT Observations
  84. GRB 081007, SMARTS optical afterglow observations
  85. GRB 081007, Swift-BAT refined analysis
  86. GRB 081007: Early RAPTOR measurements of optical counterpart
  87. GRB 081007: Swift-XRT Team refined analysis
  88. GRB 081007: Gemini-south redshift
  89. GRB 081007: Enhanced Swift-XRT position
  90. GRB 081007, Faulkes Telescope North optical observations
  91. GRB 081007, SMARTS optical/IR afterglow observations
  92. GRB 081007: REM NIR and optical counterpart
  93. GRB 081007: Swift detection of a burst with optical afterglow
  94. GRB081003C: GLAST Burst Monitor detection
  95. Fermi GBM detection of additional bursts from AXP 1E1547.0-5408
  96. INTEGRAL ToO observation of the AXP 1E 1547.0-5408
  97. GRB 081003B: TAROT Calern observatory optical observations
  98. AXP 1E 1547.0-5408: Swift/UVOT Upper Limits
  99. GRB 081003B: Swift-XRT upper limit
  100. GRB 081003A: OSN optical observations

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