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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"

32578 results found.

  1. GRB 260510B: SVOM/ECLAIRs refined analysis
  2. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  3. GRB 260511A: Fermi GBM Detection
  4. GRB 260511B SVOM/C-GFT optical counterpart detection
  5. EP260509a: LCO optical upper limits
  6. GRB 260511A: UTGO H50 optical afterglow observation
  7. GRB 260510C: AstroSat CZTI detection
  8. GRB 260511B: SVOM detection of a burst
  9. GRB 260510C: EP-FXT follow-up observation
  10. GRB 260510C: SVOM/VT optical counterpart confirmation
  11. EP260509a: EP-FXT non-detection and upper limit
  12. GRB 260511A: SVOM/VT optical observation with VHF data
  13. Fermi GRB 260511A: Global MASTER-Net observations report
  14. GRB 260511A: KAIT optical afterglow observations
  15. GRB 260511A: LCO optical afterglow detection
  16. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  17. GRB 260511A: TRT optical counterpart detection
  18. GRB 260511A: SVOM detection of a bright burst
  19. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  20. GRB 260510B: SVOM/VT optical upper limits
  21. GRB 260510C: SVOM/VT optical upper limits
  22. GRB 260510C: MAXI/GSC detection
  23. EP260509a: Global MASTER-Net observations report
  24. Fermi GBM Sub-Threshold Detection of GRB 260510B
  25. GRB 260510B: GOTO early upper limit
  26. GRB 260510C: SVOM detection of a burst
  27. GRB 260510A: GECAM-B observation
  28. GRB 260510B: LCO optical upper limits
  29. GRB 260509A: Liverpool Telescope optical observations
  30. GRB 260510B: SVOM detection of a burst
  31. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  32. GRB 260509A: LCO optical observations
  33. SVOM GRB 260509A: MASTER-OAFA optical observation
  34. Fermi GRB 260510A: Global MASTER-Net observations report
  35. GRB 260509A: KAIT optical observations
  36. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  37. GRB 260509A: SVOM/VT optical candidate with VHF data
  38. GRB 260509A: LCO optical counterpart detection
  39. GRB 260509A: GOTO optical counterpart candidate
  40. GRB 260509A: SVOM detection of a burst
  41. GRB 260506B: AstroSat CZTI detection
  42. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  43. EP260507a: REM optical/NIR observations
  44. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  45. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  46. EP260507a: COLIBRÍ optical observations
  47. EP260507a: SVOM/VT optical observations
  48. EP260507a: NOT optical observations
  49. EP260507a: further Liverpool Telescope observations
  50. EP260507a: Liverpool Telescope optical upper limits
  51. EP260507a: GOTO optical counterpart detection
  52. EP260507a: TRT optical counterpart detection
  53. EP260507a: Kinder optical counterpart candidate
  54. EP260507a: LCO optical counterpart
  55. GRB 260504B: AstroSat CZTI detection
  56. GRB 260504B: SVOM/ECLAIRs refined analysis
  57. EP260502a is likely a flaring star
  58. Fermi GRB 260506A: Global MASTER-Net observations report
  59. GRB 260503A: GECAM-B observation of a burst
  60. GRB 260430B: Glowbug gamma-ray detection
  61. GRB 260504B: SVOM/VT optical upper limits
  62. GRB 260421B: radio observation with the VLA
  63. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  64. Konus-Wind detection of GRB 260504B (short/hard)
  65. GRB 260504B: GECAM-B detection
  66. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  67. GRB 260504B: SVOM/GRM spectral analysis
  68. GRB 260504B: SVOM/MXT refined analysis and potential detection
  69. GRB 260504B: EP-FXT upper limit
  70. GRB 260502A: SVOM/GRM observation of a short GRB
  71. GRB 260503A: SVOM/GRM observation of a GRB
  72. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  73. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  74. GRB 260504B: REM optical/NIR observations
  75. IPN triangulation of GRB 260429A
  76. IPN triangulation of GRB 260428A
  77. GRB 260504B: AST3-2 i-band upper limit
  78. GRB 260504B: LCO z-band upper limit
  79. SVOM GRB 260504B: MASTER-OAFA optical observations
  80. Fermi GRB 260504A: Global MASTER-Net observations report
  81. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  82. GRB 260502A: GECAM-B observation of a short burst
  83. IPN triangulation of a bright burst from SGR 1E1841-045
  84. GRB 260429B / EP260429a: EP-FXT follow-up observation
  85. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  86. GRB 260429B / EP260429a: AstroSat CZTI detection
  87. EP260502a: BOOTES-7: early optical upper limit
  88. EP260502a: Las Cumbres upper limit
  89. GRB 260429A: SVOM/GRM observation of a short burst
  90. EP260429a: Global MASTER-Net observations report
  91. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  92. GRB 260424B: AstroSat CZTI detection
  93. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  94. EP260429a: LCO optical upper limits
  95. EP260430a: LCO optical upper limits
  96. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  97. Fermi GRB 260429A: Global MASTER-Net observations report
  98. EP260430a: Global MASTER-Net observations report
  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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