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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

42855 results found.

  1. GRB 260511A: SVOM/VT optical observation with VHF data
  2. Fermi GRB 260511A: Global MASTER-Net observations report
  3. GRB 260511A: KAIT optical afterglow observations
  4. GRB 260511A: LCO optical afterglow detection
  5. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  6. GRB 260511A: TRT optical counterpart detection
  7. GRB 260511A: SVOM detection of a bright burst
  8. GRB 260511A: BALROG localization (Fermi Trigger 800172815 / GRB 260511259)
  9. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  10. GRB 260511A: Fermi GBM Final Real-time Localization
  11. GRB 260510B: SVOM/VT optical upper limits
  12. GRB 260510C: SVOM/VT optical upper limits
  13. GRB 260510C: MAXI/GSC detection
  14. EP260509a: Global MASTER-Net observations report
  15. Fermi GBM Sub-Threshold Detection of GRB 260510B
  16. GRB 260510D: Fermi GBM Final Real-time Localization
  17. GRB 260510B: GOTO early upper limit
  18. GRB 260510C: SVOM detection of a burst
  19. GRB 260510C: Fermi GBM Final Real-time Localization
  20. GRB 260510A: GECAM-B observation
  21. GRB 260510B: LCO optical upper limits
  22. EP260509a: Einstein Probe detection of an X-ray transient
  23. GRB 260509A: Liverpool Telescope optical observations
  24. GRB 260510B: SVOM detection of a burst
  25. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  26. GRB 260509A: LCO optical observations
  27. SVOM GRB 260509A: MASTER-OAFA optical observation
  28. Fermi GRB 260510A: Global MASTER-Net observations report
  29. GRB 260509A: KAIT optical observations
  30. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  31. GRB 260510A: Fermi GBM Final Real-time Localization
  32. GRB 260509A: SVOM/VT optical candidate with VHF data
  33. GRB 260509A: LCO optical counterpart detection
  34. GRB 260509A: GOTO optical counterpart candidate
  35. GRB 260509A: SVOM detection of a burst
  36. GRB 260506B: AstroSat CZTI detection
  37. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  38. EP260507a: REM optical/NIR observations
  39. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  40. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  41. EP260507a: COLIBRÍ optical observations
  42. EP260507a: SVOM/VT optical observations
  43. EP260507a: NOT optical observations
  44. EP260507a: further Liverpool Telescope observations
  45. EP260507a: Liverpool Telescope optical upper limits
  46. GRB 260507A: Fermi GBM Final Real-time Localization
  47. EP260507a: GOTO optical counterpart detection
  48. EP260507a: TRT optical counterpart detection
  49. EP260507a: Kinder optical counterpart candidate
  50. EP260507a: LCO optical counterpart
  51. EP260507a: Einstein Probe detection of an X-ray transient
  52. GRB 260504B: AstroSat CZTI detection
  53. GRB 260504B: SVOM/ECLAIRs refined analysis
  54. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  55. GRB 260506B: Fermi GBM Final Real-time Localization
  56. EP260502a is likely a flaring star
  57. Fermi GRB 260506A: Global MASTER-Net observations report
  58. GRB 260506A: Fermi GBM Final Real-time Localization
  59. GRB 260503A: GECAM-B observation of a burst
  60. IceCube Alert 260505A: Global MASTER-Net observations report
  61. GRB 260430B: Glowbug gamma-ray detection
  62. GRB 260504B: SVOM/VT optical upper limits
  63. GRB 260421B: radio observation with the VLA
  64. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  65. Konus-Wind detection of GRB 260504B (short/hard)
  66. GRB 260504B: GECAM-B detection
  67. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  68. GRB 260504C: SVOM/GRM observation of short GRB
  69. GRB 260504B: SVOM/GRM spectral analysis
  70. GRB 260430B: AstroSat CZTI detection of a long burst
  71. GRB 260504B: SVOM/MXT refined analysis and potential detection
  72. GRB 260504B: EP-FXT upper limit
  73. GRB 260502A: SVOM/GRM observation of a short GRB
  74. GRB 260503A: SVOM/GRM observation of a GRB
  75. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  76. Konus-Wind detection of GRB 260415C
  77. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  78. Konus-Wind detection of GRB 260411C
  79. GRB 260504B: REM optical/NIR observations
  80. IPN triangulation of GRB 260429A
  81. IPN triangulation of GRB 260428A
  82. GRB 260504B: AST3-2 i-band upper limit
  83. GRB 260504B: LCO z-band upper limit
  84. SVOM GRB 260504B: MASTER-OAFA optical observations
  85. GRB 260504B: SVOM detection of a short burst
  86. Fermi GRB 260504A: Global MASTER-Net observations report
  87. GRB 260504A: Fermi GBM Final Real-time Localization
  88. GRB 260503A: Fermi GBM Final Real-time Localization
  89. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  90. GRB 260502A: GECAM-B observation of a short burst
  91. IPN triangulation of a bright burst from SGR 1E1841-045
  92. GRB 260502A: Fermi GBM Final Localization
  93. The EP-WXT trigger 01709261576 is likely a flaring star
  94. GRB 260429B / EP260429a: EP-FXT follow-up observation
  95. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  96. GRB 260429B / EP260429a: AstroSat CZTI detection
  97. EP260502a: BOOTES-7: early optical upper limit
  98. EP260502a: Einstein Probe detection of an X-ray transient
  99. GRB 260429A: SVOM/GRM observation of a short burst
  100. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China

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