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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"

28076 results found.

  1. EP260514a: Einstein Probe detection of a fast X-ray transient
  2. EP260512a: LCO optical upper limits
  3. IPN triangulation of GRB 260512A
  4. GRB 260512A: AstroSat CZTI detection
  5. EP260512a: EP-FXT follow-up observation
  6. EP260507a: Xinglong Schmidt optical counterpart detection
  7. GRB 260514A: Fermi GBM Final Real-time Localization
  8. GRB 260513A: Fermi GBM Final Real-time Localization
  9. GRB 260509A: SVOM/VT optical observations
  10. Konus-Wind detection of GRB 260511B
  11. EP260512a: Einstein Probe detection of an X-ray transient
  12. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  13. GRB 260512A: NuSTAR detection of prompt emission
  14. GRB 260512A: Fermi GBM Final Real-time Localization
  15. GRB 260511A: Glowbug gamma-ray detection
  16. Konus-Wind detection of GRB 260511A
  17. MASS-Cube (GRID 2.0) detection of GRB 260511A
  18. MASS-Cube (GRID 2.0) detection of GRB 260507A
  19. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  20. GRB 260511B: FRAM-ORM optical detection
  21. GRB 260511B: LCO optical counterpart detection
  22. GRB 260511A: SVOM/VT optical observations
  23. GRB 260511B: GOTO optical counterpart detection
  24. GRB 260510A: AstroSat CZTI detection (Erroneous Submission)
  25. GRB 260511B: SVOM/VT optical observations
  26. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  27. GRB 260511A: REM near-infrared detection
  28. GRB 260511B: AstroSat CZTI detection
  29. GRB 260506B: Glowbug gamma-ray detection
  30. GRB 260506A: Glowbug gamma-ray detection of a short burst
  31. GRB 260511B: NuSTAR detection of prompt emission
  32. GRB 260511A: NuSTAR detection of prompt emission
  33. GRB 260511B: Fermi GBM Detection
  34. GRB 260511C: Fermi GBM Final Real-time Localization
  35. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  36. GRB 260511A: Fermi GBM Detection
  37. GRB 260511B SVOM/C-GFT optical counterpart detection
  38. EP260509a: LCO optical upper limits
  39. GRB 260511A: UTGO H50 optical afterglow observation
  40. GRB 260510C: AstroSat CZTI detection
  41. GRB 260511B: SVOM detection of a burst
  42. GRB 260511B: Fermi GBM Final Real-time Localization
  43. EP260509a: EP-FXT non-detection and upper limit
  44. GRB 260511A: KAIT optical afterglow observations
  45. GRB 260511A: LCO optical afterglow detection
  46. GRB 260511A: TRT optical counterpart detection
  47. GRB 260511A: SVOM detection of a bright burst
  48. GRB 260511A: Fermi GBM Final Real-time Localization
  49. GRB 260510B: SVOM/VT optical upper limits
  50. GRB 260510C: MAXI/GSC detection
  51. Fermi GBM Sub-Threshold Detection of GRB 260510B
  52. GRB 260510D: Fermi GBM Final Real-time Localization
  53. GRB 260510B: GOTO early upper limit
  54. GRB 260510C: SVOM detection of a burst
  55. GRB 260510C: Fermi GBM Final Real-time Localization
  56. EP260509a: Einstein Probe detection of an X-ray transient
  57. GRB 260510B: SVOM detection of a burst
  58. GRB 260509A: KAIT optical observations
  59. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  60. GRB 260510A: Fermi GBM Final Real-time Localization
  61. GRB 260509A: LCO optical counterpart detection
  62. GRB 260509A: SVOM detection of a burst
  63. GRB 260506B: AstroSat CZTI detection
  64. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  65. EP260507a: NOT optical observations
  66. EP260507a: further Liverpool Telescope observations
  67. GRB 260507A: Fermi GBM Final Real-time Localization
  68. EP260507a: GOTO optical counterpart detection
  69. EP260507a: TRT optical counterpart detection
  70. EP260507a: Einstein Probe detection of an X-ray transient
  71. GRB 260504B: AstroSat CZTI detection
  72. GRB 260506B: Fermi GBM Final Real-time Localization
  73. GRB 260506A: Fermi GBM Final Real-time Localization
  74. GRB 260430B: Glowbug gamma-ray detection
  75. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  76. Konus-Wind detection of GRB 260504B (short/hard)
  77. GRB 260504B: GECAM-B detection
  78. GRB 260430B: AstroSat CZTI detection of a long burst
  79. GRB 260504B: SVOM/MXT refined analysis and potential detection
  80. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  81. Konus-Wind detection of GRB 260415C
  82. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  83. Konus-Wind detection of GRB 260411C
  84. IPN triangulation of GRB 260429A
  85. IPN triangulation of GRB 260428A
  86. GRB 260504B: AST3-2 i-band upper limit
  87. GRB 260504B: SVOM detection of a short burst
  88. GRB 260504A: Fermi GBM Final Real-time Localization
  89. GRB 260503A: Fermi GBM Final Real-time Localization
  90. GRB 260502A: Fermi GBM Final Localization
  91. GRB 260429B / EP260429a: EP-FXT follow-up observation
  92. GRB 260429B / EP260429a: AstroSat CZTI detection
  93. EP260502a: BOOTES-7: early optical upper limit
  94. EP260502a: Einstein Probe detection of an X-ray transient
  95. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  96. GRB 260424B: AstroSat CZTI detection
  97. GRB 260429A: Fermi GBM Detection
  98. EP260430a: Einstein Probe detection of an X-ray transient
  99. EP260429a: EP-WXT detection of a fast X-ray transient
  100. GRB 260429A: Fermi GBM Final Real-time Localization

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