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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"

44400 results found.

  1. GRB 260510B: GOTO early upper limit
  2. GRB 260510C: SVOM detection of a burst
  3. GRB 260510C: Fermi GBM Final Real-time Localization
  4. GRB 260510A: GECAM-B observation
  5. GRB 260510B: LCO optical upper limits
  6. EP260509a: Einstein Probe detection of an X-ray transient
  7. GRB 260509A: Liverpool Telescope optical observations
  8. GRB 260510B: SVOM detection of a burst
  9. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  10. GRB 260509A: LCO optical observations
  11. SVOM GRB 260509A: MASTER-OAFA optical observation
  12. Fermi GRB 260510A: Global MASTER-Net observations report
  13. GRB 260509A: KAIT optical observations
  14. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  15. GRB 260510A: Fermi GBM Final Real-time Localization
  16. GRB 260509A: SVOM/VT optical candidate with VHF data
  17. GRB 260509A: LCO optical counterpart detection
  18. GRB 260509A: GOTO optical counterpart candidate
  19. GRB 260509A: SVOM detection of a burst
  20. GRB 260506B: AstroSat CZTI detection
  21. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  22. EP260507a: REM optical/NIR observations
  23. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  24. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  25. EP260507a: COLIBRÍ optical observations
  26. EP260507a: SVOM/VT optical observations
  27. EP260507a: NOT optical observations
  28. EP260507a: further Liverpool Telescope observations
  29. EP260507a: Liverpool Telescope optical upper limits
  30. GRB 260507A: Fermi GBM Final Real-time Localization
  31. EP260507a: GOTO optical counterpart detection
  32. EP260507a: TRT optical counterpart detection
  33. EP260507a: Kinder optical counterpart candidate
  34. EP260507a: LCO optical counterpart
  35. EP260507a: Einstein Probe detection of an X-ray transient
  36. GRB 260504B: AstroSat CZTI detection
  37. GRB 260504B: SVOM/ECLAIRs refined analysis
  38. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  39. GRB 260506B: Fermi GBM Final Real-time Localization
  40. EP260502a is likely a flaring star
  41. Fermi GRB 260506A: Global MASTER-Net observations report
  42. GRB 260506A: Fermi GBM Final Real-time Localization
  43. GRB 260503A: GECAM-B observation of a burst
  44. IceCube Alert 260505A: Global MASTER-Net observations report
  45. GRB 260430B: Glowbug gamma-ray detection
  46. GRB 260504B: SVOM/VT optical upper limits
  47. GRB 260421B: radio observation with the VLA
  48. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  49. Konus-Wind detection of GRB 260504B (short/hard)
  50. GRB 260504B: GECAM-B detection
  51. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  52. GRB 260504C: SVOM/GRM observation of short GRB
  53. GRB 260504B: SVOM/GRM spectral analysis
  54. GRB 260430B: AstroSat CZTI detection of a long burst
  55. GRB 260504B: SVOM/MXT refined analysis and potential detection
  56. GRB 260504B: EP-FXT upper limit
  57. GRB 260502A: SVOM/GRM observation of a short GRB
  58. GRB 260503A: SVOM/GRM observation of a GRB
  59. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  60. Konus-Wind detection of GRB 260415C
  61. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  62. Konus-Wind detection of GRB 260411C
  63. GRB 260504B: REM optical/NIR observations
  64. IPN triangulation of GRB 260429A
  65. IPN triangulation of GRB 260428A
  66. GRB 260504B: AST3-2 i-band upper limit
  67. GRB 260504B: LCO z-band upper limit
  68. SVOM GRB 260504B: MASTER-OAFA optical observations
  69. GRB 260504B: SVOM detection of a short burst
  70. Fermi GRB 260504A: Global MASTER-Net observations report
  71. GRB 260504A: Fermi GBM Final Real-time Localization
  72. GRB 260503A: Fermi GBM Final Real-time Localization
  73. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  74. GRB 260502A: GECAM-B observation of a short burst
  75. IPN triangulation of a bright burst from SGR 1E1841-045
  76. GRB 260502A: Fermi GBM Final Localization
  77. The EP-WXT trigger 01709261576 is likely a flaring star
  78. GRB 260429B / EP260429a: EP-FXT follow-up observation
  79. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  80. GRB 260429B / EP260429a: AstroSat CZTI detection
  81. EP260502a: BOOTES-7: early optical upper limit
  82. EP260502a: Las Cumbres upper limit
  83. EP260502a: Einstein Probe detection of an X-ray transient
  84. GRB 260429A: SVOM/GRM observation of a short burst
  85. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  86. EP260429a: Global MASTER-Net observations report
  87. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  88. GRB 260424B: AstroSat CZTI detection
  89. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  90. EP260429a: LCO optical upper limits
  91. EP260430a: LCO optical upper limits
  92. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  93. GRB 260429A: Fermi GBM Detection
  94. Fermi GRB 260429A: Global MASTER-Net observations report
  95. EP260430a: Global MASTER-Net observations report
  96. EP260430a: Einstein Probe detection of an X-ray transient
  97. EP260429a: EP-WXT detection of a fast X-ray transient
  98. GRB 260429A: Fermi GBM Final Real-time Localization
  99. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  100. GRB 260428A: GECAM-B detection of a possible long duration Type I burst

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