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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"

32568 results found.

  1. EP260509a: EP-FXT non-detection and upper limit
  2. GRB 260511A: SVOM/VT optical observation with VHF data
  3. Fermi GRB 260511A: Global MASTER-Net observations report
  4. GRB 260511A: KAIT optical afterglow observations
  5. GRB 260511A: LCO optical afterglow detection
  6. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  7. GRB 260511A: TRT optical counterpart detection
  8. GRB 260511A: SVOM detection of a bright burst
  9. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  10. GRB 260510B: SVOM/VT optical upper limits
  11. GRB 260510C: SVOM/VT optical upper limits
  12. GRB 260510C: MAXI/GSC detection
  13. EP260509a: Global MASTER-Net observations report
  14. Fermi GBM Sub-Threshold Detection of GRB 260510B
  15. GRB 260510B: GOTO early upper limit
  16. GRB 260510C: SVOM detection of a burst
  17. GRB 260510A: GECAM-B observation
  18. GRB 260510B: LCO optical upper limits
  19. GRB 260509A: Liverpool Telescope optical observations
  20. GRB 260510B: SVOM detection of a burst
  21. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  22. GRB 260509A: LCO optical observations
  23. SVOM GRB 260509A: MASTER-OAFA optical observation
  24. Fermi GRB 260510A: Global MASTER-Net observations report
  25. GRB 260509A: KAIT optical observations
  26. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  27. GRB 260509A: SVOM/VT optical candidate with VHF data
  28. GRB 260509A: LCO optical counterpart detection
  29. GRB 260509A: GOTO optical counterpart candidate
  30. GRB 260509A: SVOM detection of a burst
  31. GRB 260506B: AstroSat CZTI detection
  32. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  33. EP260507a: REM optical/NIR observations
  34. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  35. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  36. EP260507a: COLIBRÍ optical observations
  37. EP260507a: SVOM/VT optical observations
  38. EP260507a: NOT optical observations
  39. EP260507a: further Liverpool Telescope observations
  40. EP260507a: Liverpool Telescope optical upper limits
  41. EP260507a: GOTO optical counterpart detection
  42. EP260507a: TRT optical counterpart detection
  43. EP260507a: Kinder optical counterpart candidate
  44. EP260507a: LCO optical counterpart
  45. GRB 260504B: AstroSat CZTI detection
  46. GRB 260504B: SVOM/ECLAIRs refined analysis
  47. EP260502a is likely a flaring star
  48. Fermi GRB 260506A: Global MASTER-Net observations report
  49. GRB 260503A: GECAM-B observation of a burst
  50. GRB 260430B: Glowbug gamma-ray detection
  51. GRB 260504B: SVOM/VT optical upper limits
  52. GRB 260421B: radio observation with the VLA
  53. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  54. Konus-Wind detection of GRB 260504B (short/hard)
  55. GRB 260504B: GECAM-B detection
  56. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  57. GRB 260504B: SVOM/GRM spectral analysis
  58. GRB 260504B: SVOM/MXT refined analysis and potential detection
  59. GRB 260504B: EP-FXT upper limit
  60. GRB 260502A: SVOM/GRM observation of a short GRB
  61. GRB 260503A: SVOM/GRM observation of a GRB
  62. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  63. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  64. GRB 260504B: REM optical/NIR observations
  65. IPN triangulation of GRB 260429A
  66. IPN triangulation of GRB 260428A
  67. GRB 260504B: AST3-2 i-band upper limit
  68. GRB 260504B: LCO z-band upper limit
  69. SVOM GRB 260504B: MASTER-OAFA optical observations
  70. Fermi GRB 260504A: Global MASTER-Net observations report
  71. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  72. GRB 260502A: GECAM-B observation of a short burst
  73. IPN triangulation of a bright burst from SGR 1E1841-045
  74. GRB 260429B / EP260429a: EP-FXT follow-up observation
  75. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  76. GRB 260429B / EP260429a: AstroSat CZTI detection
  77. EP260502a: BOOTES-7: early optical upper limit
  78. EP260502a: Las Cumbres upper limit
  79. GRB 260429A: SVOM/GRM observation of a short burst
  80. EP260429a: Global MASTER-Net observations report
  81. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  82. GRB 260424B: AstroSat CZTI detection
  83. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  84. EP260429a: LCO optical upper limits
  85. EP260430a: LCO optical upper limits
  86. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  87. Fermi GRB 260429A: Global MASTER-Net observations report
  88. EP260430a: Global MASTER-Net observations report
  89. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  90. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  91. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  92. GRB 260428A: AstroSat CZTI detection
  93. Fermi GRB 260428A: Global MASTER-Net observations report
  94. EP260416a: Mondy and Terskol optical upper limits
  95. GRB 260424B: Glowbug gamma-ray detection of a short burst
  96. GRB 260424B: COLIBRÍ optical upper limit
  97. Konus-Wind detection of GRB 260424B
  98. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  99. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  100. IPN triangulation of GRB 260424B (short)

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