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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"

28066 results found.

  1. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  2. GRB 260706A: ATCA detection of possible radio counterpart
  3. GRB 260714A: Fermi GBM Final Real-time Localization
  4. EP260713a: Einstein Probe detection of an X-ray transient
  5. EP260623a: KAIT optical observations
  6. EP260711a: EP-FXT follow-up observation
  7. GRB 260708A: GRANDMA Optical Observations
  8. GRB 260710A: Insight-HXMT/HE detection
  9. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  10. EP260711a: Einstein Probe detection of an X-ray transient
  11. GRB 260710A: Fermi GBM Detection
  12. GRB 260709A: SVOM/GRM detection
  13. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  14. GRB 260705C: AstroSat CZTI detection
  15. GRB 260710A: Fermi GBM Final Real-time Localization
  16. GRB 260708A: Glowbug gamma-ray detection
  17. GRB 260708A: Kilonova-Catcher optical afterglow detection
  18. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  19. GRB 260709A: Fermi GBM Final Real-time Localization
  20. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  21. GRB260708B: MAXI/GSC detection
  22. GRB 260708A: Fermi-LAT detection
  23. GRB 260708A: Fermi-GBM detection
  24. GRB 260706A: Further EP-FXT follow-up observation
  25. GRB 260706A: SVOM/VT optical upper limits
  26. EP260707a: Einstein Probe detection of an X-ray transient
  27. GRB 260705C: Glowbug gamma-ray detection of a short burst
  28. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  29. IceCube-260704A: No candidates from the Zwicky Transient Facility
  30. GRB 260707A: Fermi GBM Final Real-time Localization
  31. GRB 260706A: SVOM detection of a burst
  32. GRB 260706A: Fermi GBM Final Real-time Localization
  33. GRB 260705C: Fermi GBM Final Localization
  34. GRB 260705B: Fermi GBM Final Real-time Localization
  35. Fermi GBM Sub-Threshold Detection of GRB 260705A
  36. GRB 260705A: SVOM detection of a burst
  37. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  38. GRB 260629A: AstroSat CZTI detection
  39. EP260703a: EP-FXT follow-up observation
  40. GRB 260704A: SVOM detection of a possible GRB
  41. GRB 260703B: Fermi GBM Final Localization
  42. EP260703a: EP-WXT detection of a fast X-ray transient
  43. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  44. GRB 260703A: Fermi GBM Final Localization
  45. GRB 260610B: VLA detection
  46. GRB 260623A: Glowbug gamma-ray detection
  47. GRB 260701A: Fermi GBM Final Real-time Localization
  48. EP260628a: EP-FXT follow-up observation
  49. GRB 260629A: Fermi GBM Final Real-time Localization
  50. EP260628a: EP-WXT detection of a fast X-ray transient
  51. GRB 260628A: Fermi GBM Final Real-time Localization
  52. EP260626a: EP-FXT follow-up observation
  53. EP260626a: Liverpool Telescope upper limits
  54. EP260626a: EP-WXT detection of a fast X-ray transient
  55. Konus-Wind detection of GRB 260623B / EP260623a
  56. EP260623a: TNG NIR afterglow detection
  57. GRB 260618A: Fermi GBM Observation
  58. MASS-Cube (GRID 2.0) detection of GRB 260616B
  59. Konus-Wind detection of GRB 260618B
  60. GRB 260624A: Fermi GBM Final Real-time Localization
  61. GRB 260617A: Glowbug gamma-ray detection of a short burst
  62. IPN triangulation of GRB 260605A
  63. EP260623a: Optical follow-up observations with Kinder
  64. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  65. GRB 260623A: Fermi GBM Final Real-time Localization
  66. EP260623a: REM optical/NIR afterglow detection
  67. EP 260623a: COLIBRÍ optical observations
  68. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  69. EP260623a: OSIRIS+/GTC redshift z = 0.703
  70. EP260623a: Einstein Probe detection of an X-ray transient
  71. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  72. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  73. GRB 260619A: NOT optical observations
  74. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  75. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  76. GRB 260604B: 239Alferov CubeSat detection
  77. GRB 260604A: 239Alferov CubeSat detection
  78. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  79. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  80. Konus-Wind detection of GRB 260617A
  81. GRB 260616B: AstroSat CZTI detection
  82. GRB 260616A: AstroSat CZTI detection
  83. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  84. EP260618a: EP-FXT follow-up observation
  85. EP260618a: LCO optical counterpart confirmation
  86. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  87. GRB 260616A: NuSTAR detection of prompt emission
  88. GRB 260614B: NuSTAR detection of prompt emission
  89. GRB 260619A: SVOM possible detection of a faint burst
  90. GRB 260618B: Fermi-LAT detection
  91. IPN triangulation of GRB 260617A (short)
  92. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  93. GRB 260616A: Insight-HXMT detection
  94. GRB 260618B: Fermi GBM Final Real-time Localization
  95. EP260618a: EP-WXT detection of an X-ray transient
  96. EP260616a/GRB 260616B: EP-FXT follow-up observation
  97. GRB 260506B: cubesat Avion detection
  98. GRB 260618A: Fermi GBM Final Real-time Localization
  99. GRB 260617A: Fermi GBM Detection
  100. GRB 260617A: Fermi GBM Final Real-time Localization

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