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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"

32688 results found.

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

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