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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"

27783 results found.

  1. GRB 260710A: Insight-HXMT/HE detection
  2. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  3. EP260711a: Einstein Probe detection of an X-ray transient
  4. GRB 260710A: Fermi GBM Detection
  5. GRB 260709A: SVOM/GRM detection
  6. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  7. GRB 260705C: AstroSat CZTI detection
  8. GRB 260710A: Fermi GBM Final Real-time Localization
  9. GRB 260708A: Glowbug gamma-ray detection
  10. GRB 260708A: Kilonova-Catcher optical afterglow detection
  11. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  12. GRB 260709A: Fermi GBM Final Real-time Localization
  13. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  14. GRB260708B: MAXI/GSC detection
  15. GRB 260708A: Fermi-LAT detection
  16. GRB 260708A: Fermi-GBM detection
  17. GRB 260706A: Further EP-FXT follow-up observation
  18. GRB 260706A: SVOM/VT optical upper limits
  19. EP260707a: Einstein Probe detection of an X-ray transient
  20. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  21. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  22. GRB 260705C: Glowbug gamma-ray detection of a short burst
  23. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  24. IceCube-260704A: No candidates from the Zwicky Transient Facility
  25. GRB 260707A: Fermi GBM Final Real-time Localization
  26. GRB 260706A: SVOM detection of a burst
  27. GRB 260706A: Fermi GBM Final Real-time Localization
  28. GRB 260705C: Fermi GBM Final Localization
  29. GRB 260705B: Fermi GBM Final Real-time Localization
  30. Fermi GBM Sub-Threshold Detection of GRB 260705A
  31. GRB 260705A: SVOM detection of a burst
  32. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  33. GRB 260629A: AstroSat CZTI detection
  34. EP260703a: EP-FXT follow-up observation
  35. GRB 260704A: SVOM detection of a possible GRB
  36. GRB 260703B: Fermi GBM Final Localization
  37. EP260703a: EP-WXT detection of a fast X-ray transient
  38. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  39. GRB 260703A: Fermi GBM Final Localization
  40. GRB 260610B: VLA detection
  41. GRB 260623A: Glowbug gamma-ray detection
  42. GRB 260701A: Fermi GBM Final Real-time Localization
  43. EP260628a: EP-FXT follow-up observation
  44. GRB 260629A: Fermi GBM Final Real-time Localization
  45. EP260628a: EP-WXT detection of a fast X-ray transient
  46. GRB 260628A: Fermi GBM Final Real-time Localization
  47. EP260626a: EP-FXT follow-up observation
  48. EP260626a: Liverpool Telescope upper limits
  49. EP260626a: EP-WXT detection of a fast X-ray transient
  50. Konus-Wind detection of GRB 260623B / EP260623a
  51. EP260623a: TNG NIR afterglow detection
  52. MASS-Cube (GRID 2.0) detection of GRB 260616B
  53. Konus-Wind detection of GRB 260618B
  54. GRB 260624A: Fermi GBM Final Real-time Localization
  55. GRB 260617A: Glowbug gamma-ray detection of a short burst
  56. IPN triangulation of GRB 260605A
  57. EP260623a: Optical follow-up observations with Kinder
  58. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  59. GRB 260623A: Fermi GBM Final Real-time Localization
  60. EP260623a: REM optical/NIR afterglow detection
  61. EP 260623a: COLIBRÍ optical observations
  62. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  63. EP260623a: Einstein Probe detection of an X-ray transient
  64. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  65. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  66. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  67. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  68. GRB 260604B: 239Alferov CubeSat detection
  69. GRB 260604A: 239Alferov CubeSat detection
  70. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  71. Konus-Wind detection of GRB 260617A
  72. GRB 260616B: AstroSat CZTI detection
  73. GRB 260616A: AstroSat CZTI detection
  74. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  75. EP260618a: EP-FXT follow-up observation
  76. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  77. GRB 260616A: NuSTAR detection of prompt emission
  78. GRB 260614B: NuSTAR detection of prompt emission
  79. GRB 260619A: SVOM possible detection of a faint burst
  80. GRB 260618B: Fermi-LAT detection
  81. IPN triangulation of GRB 260617A (short)
  82. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  83. GRB 260616A: Insight-HXMT detection
  84. GRB 260618B: Fermi GBM Final Real-time Localization
  85. EP260618a: EP-WXT detection of an X-ray transient
  86. EP260616a/GRB 260616B: EP-FXT follow-up observation
  87. GRB 260506B: cubesat Avion detection
  88. GRB 260618A: Fermi GBM Final Real-time Localization
  89. GRB 260617A: Fermi GBM Detection
  90. GRB 260617A: Fermi GBM Final Real-time Localization
  91. Konus-Wind detection of GRB 260616B/EP260616a
  92. Konus-Wind detection of GRB 260616A
  93. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  94. GRB 260429A: cubesat Avion detection
  95. GRB260616C: MAXI/GSC detection
  96. GRB 260616A: Fermi-LAT detection
  97. GRB 260614A: AstroSat CZTI detection
  98. EP260616a: EP-WXT detection of a fast X-ray transient
  99. GRB 260616B: Fermi GBM Detection
  100. GRB 260616A: Fermi GBM Final Real-time Localization

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