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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"

42859 results found.

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

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