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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

14823 results found.

  1. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  2. GRB260708B: MAXI/GSC detection
  3. GRB 260708A: Fermi-LAT detection
  4. GRB 260708A: Fermi-GBM detection
  5. GRB 260706A: Further EP-FXT follow-up observation
  6. GRB 260706A: SVOM/VT optical upper limits
  7. EP260707a (by EP-FXT): NOT optical upper limit
  8. EP260707a: TRT optical upper limit
  9. EP260707a: Einstein Probe detection of an X-ray transient
  10. GRB 260705C: Glowbug gamma-ray detection of a short burst
  11. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  12. IceCube-260704A: No candidates from the Zwicky Transient Facility
  13. GRB 260707A: Fermi GBM Final Real-time Localization
  14. GRB 260706A: SVOM detection of a burst
  15. GRB 260706A: Fermi GBM Final Real-time Localization
  16. GRB 260705C: Fermi GBM Final Localization
  17. GRB 260705B: Fermi GBM Final Real-time Localization
  18. Fermi GBM Sub-Threshold Detection of GRB 260705A
  19. GRB 260705A: SVOM detection of a burst
  20. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  21. GRB 260629A: AstroSat CZTI detection
  22. EP260703a: EP-FXT follow-up observation
  23. GRB 260704A: SVOM detection of a possible GRB
  24. GRB 260703B: Fermi GBM Final Localization
  25. EP260703a: EP-WXT detection of a fast X-ray transient
  26. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  27. GRB 260703A: Fermi GBM Final Localization
  28. GRB 260610B: VLA detection
  29. GRB 260623A: Glowbug gamma-ray detection
  30. GRB 260701A: Fermi GBM Final Real-time Localization
  31. EP260628a: EP-FXT follow-up observation
  32. GRB 260629A: Fermi GBM Final Real-time Localization
  33. EP260628a: EP-WXT detection of a fast X-ray transient
  34. GRB 260628A: Fermi GBM Final Real-time Localization
  35. EP260626a: EP-FXT follow-up observation
  36. EP260626a: Liverpool Telescope upper limits
  37. EP260626a: EP-WXT detection of a fast X-ray transient
  38. Konus-Wind detection of GRB 260623B / EP260623a
  39. EP260623a: TNG NIR afterglow detection
  40. MASS-Cube (GRID 2.0) detection of GRB 260616B
  41. Konus-Wind detection of GRB 260618B
  42. GRB 260624A: Fermi GBM Final Real-time Localization
  43. GRB 260617A: Glowbug gamma-ray detection of a short burst
  44. IPN triangulation of GRB 260605A
  45. EP260623a: Optical follow-up observations with Kinder
  46. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  47. GRB 260623A: Fermi GBM Final Real-time Localization
  48. EP260623a: TRT optical observations
  49. EP260623a: REM optical/NIR afterglow detection
  50. EP 260623a: COLIBRÍ optical observations
  51. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  52. EP260623a: Einstein Probe detection of an X-ray transient
  53. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  54. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  55. EP260618a: Liverpool Telescope optical observations
  56. GRB 260619A: NOT optical observations
  57. EP260618a: JinShan optical observations
  58. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  59. GRB 260619A: TRT optical counterpart confirmation
  60. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  61. GRB 260604B: 239Alferov CubeSat detection
  62. GRB 260604A: 239Alferov CubeSat detection
  63. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  64. Konus-Wind detection of GRB 260617A
  65. GRB 260616B: AstroSat CZTI detection
  66. GRB 260616A: AstroSat CZTI detection
  67. GRB 260616A: SVOM/GRM observation
  68. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  69. EP260618a: EP-FXT follow-up observation
  70. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  71. GRB 260616A: NuSTAR detection of prompt emission
  72. GRB 260614B: NuSTAR detection of prompt emission
  73. GRB 260619A: SVOM possible detection of a faint burst
  74. GRB 260618B: Fermi-LAT detection
  75. IPN triangulation of GRB 260617A (short)
  76. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  77. GRB 260616A: Insight-HXMT detection
  78. GRB 260618B: Fermi GBM Final Real-time Localization
  79. EP260618a: EP-WXT detection of an X-ray transient
  80. EP260616a/GRB 260616B: EP-FXT follow-up observation
  81. GRB 260506B: cubesat Avion detection
  82. GRB 260618A: Fermi GBM Final Real-time Localization
  83. GRB 260617A: Fermi GBM Detection
  84. GRB 260617A: Fermi GBM Final Real-time Localization
  85. Konus-Wind detection of GRB 260616B/EP260616a
  86. Konus-Wind detection of GRB 260616A
  87. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  88. GRB 260429A: cubesat Avion detection
  89. GRB260616C: MAXI/GSC detection
  90. GRB 260616A: Fermi-LAT detection
  91. GRB 260614A: AstroSat CZTI detection
  92. EP260616a: EP-WXT detection of a fast X-ray transient
  93. GRB 260616B: Fermi GBM Detection
  94. GRB 260616A: Fermi GBM Final Real-time Localization
  95. GRB 260610B: ALMA detection
  96. GRB 260614B: SVOM detection of a burst
  97. GRB 260614B: Fermi GBM Final Real-time Localization
  98. GRB 260611B: SVOM/GRM detection
  99. GRB 260614A: Fermi GBM Final Localization
  100. GRB 260603C: AstroSat CZTI detection

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