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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"

45496 results found.

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

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