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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"

24278 results found.

  1. GRB 260510C: SVOM/VT optical upper limits
  2. GRB 260510C: MAXI/GSC detection
  3. EP260509a: Global MASTER-Net observations report
  4. Fermi GBM Sub-Threshold Detection of GRB 260510B
  5. GRB 260510D: Fermi GBM Final Real-time Localization
  6. GRB 260510B: GOTO early upper limit
  7. GRB 260510C: SVOM detection of a burst
  8. GRB 260510C: Fermi GBM Final Real-time Localization
  9. GRB 260510B: LCO optical upper limits
  10. GRB 260510B: SVOM detection of a burst
  11. GRB 260509A: LCO optical observations
  12. SVOM GRB 260509A: MASTER-OAFA optical observation
  13. Fermi GRB 260510A: Global MASTER-Net observations report
  14. GRB 260509A: KAIT optical 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: SVOM/VT optical observations
  26. GRB 260507A: Fermi GBM Final Real-time Localization
  27. EP260507a: TRT optical counterpart detection
  28. GRB 260504B: SVOM/ECLAIRs refined analysis
  29. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  30. GRB 260506B: Fermi GBM Final Real-time Localization
  31. EP260502a is likely a flaring star
  32. Fermi GRB 260506A: Global MASTER-Net observations report
  33. GRB 260506A: Fermi GBM Final Real-time Localization
  34. IceCube Alert 260505A: Global MASTER-Net observations report
  35. GRB 260504B: SVOM/VT optical upper limits
  36. Konus-Wind detection of GRB 260504B (short/hard)
  37. GRB 260504B: GECAM-B detection
  38. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  39. GRB 260504B: SVOM/GRM spectral analysis
  40. GRB 260504B: SVOM/MXT refined analysis and potential detection
  41. GRB 260504B: EP-FXT upper limit
  42. GRB 260502A: SVOM/GRM observation of a short GRB
  43. GRB 260503A: SVOM/GRM observation of a GRB
  44. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  45. Konus-Wind detection of GRB 260415C
  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. IPN triangulation of a bright burst from SGR 1E1841-045
  59. GRB 260502A: Fermi GBM Final Localization
  60. The EP-WXT trigger 01709261576 is likely a flaring star
  61. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  62. EP260502a: BOOTES-7: early optical upper limit
  63. GRB 260429A: SVOM/GRM observation of a short burst
  64. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  65. EP260429a: Global MASTER-Net observations report
  66. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  67. GRB 260429A: Fermi GBM Detection
  68. Fermi GRB 260429A: Global MASTER-Net observations report
  69. EP260430a: Global MASTER-Net observations report
  70. GRB 260429A: Fermi GBM Final Real-time Localization
  71. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  72. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  73. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  74. Fermi GRB 260428A: Global MASTER-Net observations report
  75. Konus-Wind detection of GRB 260424B
  76. GRB 260428A: Fermi GBM Final Real-time Localization
  77. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  78. GRB 260424C: Fermi GBM Final Localization
  79. IPN triangulation of GRB 260424B (short)
  80. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  81. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  82. IceCube Alert 260425A: Global MASTER-Net observations report
  83. Fermi trigger No 798737427: Global MASTER-Net observations report
  84. GRB 260401A: cubesat Avion detection
  85. GRB 260424A: AstroSat CZTI detection of a long burst
  86. GRB 260421B: SVOM/ECLAIRs refined analysis
  87. GRB 260421B: 3.6m DOT optical observation
  88. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  89. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  90. GRB 260421B: SVOM/GRM observation
  91. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  92. GRB 260421B: EP-FXT follow-up observation
  93. The EP-WXT trigger 01709260362 is likely a flaring star
  94. GRB 260421B: Fermi GBM Observation
  95. GRB 260412A: SVOM/ECLAIRs refined analysis
  96. GRB 260421B: SVOM/VT optical observations
  97. GRB 260310A: Late-time Chandra X-ray Detection
  98. EP260416a: 1.3m DFOT optical observation
  99. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  100. GRB 260415B: CALET Gamma-Ray Burst Monitor detection

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