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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"

19279 results found.

  1. GRB 260510C: Fermi GBM Final Real-time Localization
  2. GRB 260510A: GECAM-B observation
  3. GRB 260510B: LCO optical upper limits
  4. EP260509a: Einstein Probe detection of an X-ray transient
  5. GRB 260509A: Liverpool Telescope optical observations
  6. GRB 260510B: SVOM detection of a burst
  7. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  8. GRB 260509A: LCO optical observations
  9. SVOM GRB 260509A: MASTER-OAFA optical observation
  10. Fermi GRB 260510A: Global MASTER-Net observations report
  11. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  12. GRB 260510A: Fermi GBM Final Real-time Localization
  13. GRB 260509A: SVOM/VT optical candidate with VHF data
  14. GRB 260509A: LCO optical counterpart detection
  15. GRB 260509A: GOTO optical counterpart candidate
  16. GRB 260509A: SVOM detection of a burst
  17. GRB 260506B: AstroSat CZTI detection
  18. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  19. EP260507a: REM optical/NIR observations
  20. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  21. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  22. EP260507a: COLIBRÍ optical observations
  23. EP260507a: SVOM/VT optical observations
  24. EP260507a: further Liverpool Telescope observations
  25. EP260507a: Liverpool Telescope optical upper limits
  26. GRB 260507A: Fermi GBM Final Real-time Localization
  27. EP260507a: GOTO optical counterpart detection
  28. EP260507a: TRT optical counterpart detection
  29. EP260507a: Kinder optical counterpart candidate
  30. EP260507a: LCO optical counterpart
  31. EP260507a: Einstein Probe detection of an X-ray transient
  32. GRB 260504B: AstroSat CZTI detection
  33. GRB 260504B: SVOM/ECLAIRs refined analysis
  34. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  35. GRB 260506B: Fermi GBM Final Real-time Localization
  36. EP260502a is likely a flaring star
  37. Fermi GRB 260506A: Global MASTER-Net observations report
  38. GRB 260506A: Fermi GBM Final Real-time Localization
  39. GRB 260503A: GECAM-B observation of a burst
  40. IceCube Alert 260505A: Global MASTER-Net observations report
  41. GRB 260430B: Glowbug gamma-ray detection
  42. GRB 260504B: SVOM/VT optical upper limits
  43. GRB 260421B: radio observation with the VLA
  44. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  45. GRB 260504B: GECAM-B detection
  46. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  47. GRB 260504C: SVOM/GRM observation of short GRB
  48. GRB 260430B: AstroSat CZTI detection of a long burst
  49. GRB 260504B: SVOM/MXT refined analysis and potential detection
  50. GRB 260504B: EP-FXT upper limit
  51. GRB 260502A: SVOM/GRM observation of a short GRB
  52. GRB 260503A: SVOM/GRM observation of a GRB
  53. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  54. Konus-Wind detection of GRB 260411C
  55. GRB 260504B: REM optical/NIR observations
  56. GRB 260504B: AST3-2 i-band upper limit
  57. GRB 260504B: LCO z-band upper limit
  58. SVOM GRB 260504B: MASTER-OAFA optical observations
  59. GRB 260504B: SVOM detection of a short burst
  60. Fermi GRB 260504A: Global MASTER-Net observations report
  61. GRB 260504A: Fermi GBM Final Real-time Localization
  62. GRB 260503A: Fermi GBM Final Real-time Localization
  63. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  64. GRB 260502A: GECAM-B observation of a short burst
  65. GRB 260502A: Fermi GBM Final Localization
  66. The EP-WXT trigger 01709261576 is likely a flaring star
  67. GRB 260429B / EP260429a: EP-FXT follow-up observation
  68. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  69. GRB 260429B / EP260429a: AstroSat CZTI detection
  70. EP260502a: BOOTES-7: early optical upper limit
  71. EP260502a: Einstein Probe detection of an X-ray transient
  72. GRB 260429A: SVOM/GRM observation of a short burst
  73. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  74. EP260429a: Global MASTER-Net observations report
  75. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  76. GRB 260424B: AstroSat CZTI detection
  77. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  78. EP260429a: LCO optical upper limits
  79. EP260430a: LCO optical upper limits
  80. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  81. GRB 260429A: Fermi GBM Detection
  82. Fermi GRB 260429A: Global MASTER-Net observations report
  83. EP260430a: Global MASTER-Net observations report
  84. EP260430a: Einstein Probe detection of an X-ray transient
  85. EP260429a: EP-WXT detection of a fast X-ray transient
  86. GRB 260429A: Fermi GBM Final Real-time Localization
  87. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  88. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  89. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  90. GRB 260428A: AstroSat CZTI detection
  91. Fermi GRB 260428A: Global MASTER-Net observations report
  92. EP260416a: Mondy and Terskol optical upper limits
  93. GRB 260424B: Glowbug gamma-ray detection of a short burst
  94. GRB 260424B: COLIBRÍ optical upper limit
  95. GRB 260428A: Fermi GBM Final Real-time Localization
  96. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  97. GRB 260424C: Fermi GBM Final Localization
  98. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  99. GRB 260424B: SVOM/GRM detection of a short burst
  100. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event

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