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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"

44398 results found.

  1. GRB 260511B: SVOM detection of a burst
  2. GRB 260511B: Fermi GBM Final Real-time Localization
  3. GRB 260510C: EP-FXT follow-up observation
  4. GRB 260510C: SVOM/VT optical counterpart confirmation
  5. EP260509a: EP-FXT non-detection and upper limit
  6. GRB 260511A: SVOM/VT optical observation with VHF data
  7. Fermi GRB 260511A: Global MASTER-Net observations report
  8. GRB 260511A: KAIT optical afterglow observations
  9. GRB 260511A: LCO optical afterglow detection
  10. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  11. GRB 260511A: TRT optical counterpart detection
  12. GRB 260511A: SVOM detection of a bright burst
  13. GRB 260511A: BALROG localization (Fermi Trigger 800172815 / GRB 260511259)
  14. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  15. GRB 260511A: Fermi GBM Final Real-time Localization
  16. GRB 260510B: SVOM/VT optical upper limits
  17. GRB 260510C: SVOM/VT optical upper limits
  18. GRB 260510C: MAXI/GSC detection
  19. EP260509a: Global MASTER-Net observations report
  20. Fermi GBM Sub-Threshold Detection of GRB 260510B
  21. GRB 260510D: Fermi GBM Final Real-time Localization
  22. GRB 260510B: GOTO early upper limit
  23. GRB 260510C: SVOM detection of a burst
  24. GRB 260510C: Fermi GBM Final Real-time Localization
  25. GRB 260510A: GECAM-B observation
  26. GRB 260510B: LCO optical upper limits
  27. EP260509a: Einstein Probe detection of an X-ray transient
  28. GRB 260509A: Liverpool Telescope optical observations
  29. GRB 260510B: SVOM detection of a burst
  30. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  31. GRB 260509A: LCO optical observations
  32. SVOM GRB 260509A: MASTER-OAFA optical observation
  33. Fermi GRB 260510A: Global MASTER-Net observations report
  34. GRB 260509A: KAIT optical observations
  35. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  36. GRB 260510A: Fermi GBM Final Real-time Localization
  37. GRB 260509A: SVOM/VT optical candidate with VHF data
  38. GRB 260509A: LCO optical counterpart detection
  39. GRB 260509A: GOTO optical counterpart candidate
  40. GRB 260509A: SVOM detection of a burst
  41. GRB 260506B: AstroSat CZTI detection
  42. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  43. EP260507a: REM optical/NIR observations
  44. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  45. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  46. EP260507a: COLIBRÍ optical observations
  47. EP260507a: SVOM/VT optical observations
  48. EP260507a: NOT optical observations
  49. EP260507a: further Liverpool Telescope observations
  50. EP260507a: Liverpool Telescope optical upper limits
  51. GRB 260507A: Fermi GBM Final Real-time Localization
  52. EP260507a: GOTO optical counterpart detection
  53. EP260507a: TRT optical counterpart detection
  54. EP260507a: Kinder optical counterpart candidate
  55. EP260507a: LCO optical counterpart
  56. EP260507a: Einstein Probe detection of an X-ray transient
  57. GRB 260504B: AstroSat CZTI detection
  58. GRB 260504B: SVOM/ECLAIRs refined analysis
  59. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  60. GRB 260506B: Fermi GBM Final Real-time Localization
  61. EP260502a is likely a flaring star
  62. Fermi GRB 260506A: Global MASTER-Net observations report
  63. GRB 260506A: Fermi GBM Final Real-time Localization
  64. GRB 260503A: GECAM-B observation of a burst
  65. IceCube Alert 260505A: Global MASTER-Net observations report
  66. GRB 260430B: Glowbug gamma-ray detection
  67. GRB 260504B: SVOM/VT optical upper limits
  68. GRB 260421B: radio observation with the VLA
  69. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  70. Konus-Wind detection of GRB 260504B (short/hard)
  71. GRB 260504B: GECAM-B detection
  72. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  73. GRB 260504C: SVOM/GRM observation of short GRB
  74. GRB 260504B: SVOM/GRM spectral analysis
  75. GRB 260430B: AstroSat CZTI detection of a long burst
  76. GRB 260504B: SVOM/MXT refined analysis and potential detection
  77. GRB 260504B: EP-FXT upper limit
  78. GRB 260502A: SVOM/GRM observation of a short GRB
  79. GRB 260503A: SVOM/GRM observation of a GRB
  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. GRB 260504B: REM optical/NIR observations
  85. IPN triangulation of GRB 260429A
  86. IPN triangulation of GRB 260428A
  87. GRB 260504B: AST3-2 i-band upper limit
  88. GRB 260504B: LCO z-band upper limit
  89. SVOM GRB 260504B: MASTER-OAFA optical observations
  90. GRB 260504B: SVOM detection of a short burst
  91. Fermi GRB 260504A: Global MASTER-Net observations report
  92. GRB 260504A: Fermi GBM Final Real-time Localization
  93. GRB 260503A: Fermi GBM Final Real-time Localization
  94. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  95. GRB 260502A: GECAM-B observation of a short burst
  96. IPN triangulation of a bright burst from SGR 1E1841-045
  97. GRB 260502A: Fermi GBM Final Localization
  98. The EP-WXT trigger 01709261576 is likely a flaring star
  99. GRB 260429B / EP260429a: EP-FXT follow-up observation
  100. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position

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