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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"

32681 results found.

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

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