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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"

45661 results found.

  1. GRB 260509A: LCO optical counterpart detection
  2. GRB 260509A: GOTO optical counterpart candidate
  3. GRB 260509A: SVOM detection of a burst
  4. GRB 260506B: AstroSat CZTI detection
  5. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  6. EP260507a: REM optical/NIR observations
  7. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  8. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  9. EP260507a: COLIBRÍ optical observations
  10. EP260507a: SVOM/VT optical observations
  11. EP260507a: NOT optical observations
  12. EP260507a: further Liverpool Telescope observations
  13. EP260507a: Liverpool Telescope optical upper limits
  14. GRB 260507A: Fermi GBM Final Real-time Localization
  15. EP260507a: GOTO optical counterpart detection
  16. EP260507a: TRT optical counterpart detection
  17. EP260507a: Kinder optical counterpart candidate
  18. EP260507a: LCO optical counterpart
  19. EP260507a: Einstein Probe detection of an X-ray transient
  20. GRB 260504B: AstroSat CZTI detection
  21. GRB 260504B: SVOM/ECLAIRs refined analysis
  22. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  23. GRB 260506B: Fermi GBM Final Real-time Localization
  24. EP260502a is likely a flaring star
  25. Fermi GRB 260506A: Global MASTER-Net observations report
  26. GRB 260506A: Fermi GBM Final Real-time Localization
  27. GRB 260503A: GECAM-B observation of a burst
  28. IceCube Alert 260505A: Global MASTER-Net observations report
  29. GRB 260430B: Glowbug gamma-ray detection
  30. GRB 260504B: SVOM/VT optical upper limits
  31. GRB 260421B: radio observation with the VLA
  32. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  33. Konus-Wind detection of GRB 260504B (short/hard)
  34. GRB 260504B: GECAM-B detection
  35. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  36. GRB 260504C: SVOM/GRM observation of short GRB
  37. GRB 260504B: SVOM/GRM spectral analysis
  38. GRB 260430B: AstroSat CZTI detection of a long burst
  39. GRB 260504B: SVOM/MXT refined analysis and potential detection
  40. GRB 260504B: EP-FXT upper limit
  41. GRB 260502A: SVOM/GRM observation of a short GRB
  42. GRB 260503A: SVOM/GRM observation of a GRB
  43. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  44. Konus-Wind detection of GRB 260415C
  45. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  46. Konus-Wind detection of GRB 260411C
  47. GRB 260504B: REM optical/NIR observations
  48. IPN triangulation of GRB 260429A
  49. IPN triangulation of GRB 260428A
  50. GRB 260504B: AST3-2 i-band upper limit
  51. GRB 260504B: LCO z-band upper limit
  52. SVOM GRB 260504B: MASTER-OAFA optical observations
  53. GRB 260504B: SVOM detection of a short burst
  54. Fermi GRB 260504A: Global MASTER-Net observations report
  55. GRB 260504A: Fermi GBM Final Real-time Localization
  56. GRB 260503A: Fermi GBM Final Real-time Localization
  57. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  58. GRB 260502A: GECAM-B observation of a short burst
  59. IPN triangulation of a bright burst from SGR 1E1841-045
  60. GRB 260502A: Fermi GBM Final Localization
  61. The EP-WXT trigger 01709261576 is likely a flaring star
  62. GRB 260429B / EP260429a: EP-FXT follow-up observation
  63. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  64. GRB 260429B / EP260429a: AstroSat CZTI detection
  65. EP260502a: BOOTES-7: early optical upper limit
  66. EP260502a: Las Cumbres upper limit
  67. EP260502a: Einstein Probe detection of an X-ray transient
  68. GRB 260429A: SVOM/GRM observation of a short burst
  69. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  70. EP260429a: Global MASTER-Net observations report
  71. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  72. GRB 260424B: AstroSat CZTI detection
  73. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  74. EP260429a: LCO optical upper limits
  75. EP260430a: LCO optical upper limits
  76. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  77. GRB 260429A: Fermi GBM Detection
  78. Fermi GRB 260429A: Global MASTER-Net observations report
  79. EP260430a: Global MASTER-Net observations report
  80. EP260430a: Einstein Probe detection of an X-ray transient
  81. EP260429a: EP-WXT detection of a fast X-ray transient
  82. GRB 260429A: Fermi GBM Final Real-time Localization
  83. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  84. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  85. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  86. GRB 260428A: AstroSat CZTI detection
  87. Fermi GRB 260428A: Global MASTER-Net observations report
  88. EP260416a: Mondy and Terskol optical upper limits
  89. GRB 260424B: Glowbug gamma-ray detection of a short burst
  90. GRB 260424B: COLIBRÍ optical upper limit
  91. Konus-Wind detection of GRB 260424B
  92. GRB 260428A: Fermi GBM Final Real-time Localization
  93. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  94. GRB 260424C: Fermi GBM Final Localization
  95. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  96. IPN triangulation of GRB 260424B (short)
  97. GRB 260424B: SVOM/GRM detection of a short burst
  98. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  99. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  100. IceCube Alert 260425A: Global MASTER-Net observations report

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