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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"

14851 results found.

  1. GRB 260718A: SVOM detection of a burst
  2. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  3. sb26071506: SVOM detection of a X-ray transient
  4. GRB 260715A: Fermi GBM Final Real-time Localization
  5. GRB 260710A: AstroSat CZTI detection
  6. GRB 260709A: AstroSat CZTI detection
  7. GRB 260714B: AstroSat CZTI detection
  8. GRB 260714B: Fermi-LAT detection
  9. GRB 260714B: Fermi GBM Detection
  10. GRB 260714B: Fermi GBM Final Real-time Localization
  11. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  12. GRB 260706A: ATCA detection of possible radio counterpart
  13. GRB 260714A: Fermi GBM Final Real-time Localization
  14. EP260713a: Einstein Probe detection of an X-ray transient
  15. GRB 260619A: SVOM/VT continuous optical observations
  16. EP260711a: EP-FXT follow-up observation
  17. GRB 260710A: Insight-HXMT/HE detection
  18. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  19. EP260711a: Einstein Probe detection of an X-ray transient
  20. GRB 260710A: Fermi GBM Detection
  21. GRB 260709A: SVOM/GRM detection
  22. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  23. GRB 260705C: AstroSat CZTI detection
  24. GRB 260710A: Fermi GBM Final Real-time Localization
  25. GRB 260708A: Glowbug gamma-ray detection
  26. GRB 260708A: Kilonova-Catcher optical afterglow detection
  27. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  28. GRB 260709A: Fermi GBM Final Real-time Localization
  29. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  30. GRB260708B: MAXI/GSC detection
  31. GRB 260708A: Fermi-LAT detection
  32. GRB 260708A: Fermi-GBM detection
  33. GRB 260706A: Further EP-FXT follow-up observation
  34. GRB 260706A: SVOM/VT optical upper limits
  35. EP260707a (by EP-FXT): NOT optical upper limit
  36. EP260707a: TRT optical upper limit
  37. EP260707a: Einstein Probe detection of an X-ray transient
  38. GRB 260705C: Glowbug gamma-ray detection of a short burst
  39. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  40. IceCube-260704A: No candidates from the Zwicky Transient Facility
  41. GRB 260707A: Fermi GBM Final Real-time Localization
  42. GRB 260706A: SVOM detection of a burst
  43. GRB 260706A: Fermi GBM Final Real-time Localization
  44. GRB 260705C: Fermi GBM Final Localization
  45. GRB 260705B: Fermi GBM Final Real-time Localization
  46. Fermi GBM Sub-Threshold Detection of GRB 260705A
  47. GRB 260705A: SVOM detection of a burst
  48. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  49. GRB 260629A: AstroSat CZTI detection
  50. EP260703a: EP-FXT follow-up observation
  51. GRB 260704A: SVOM detection of a possible GRB
  52. GRB 260703B: Fermi GBM Final Localization
  53. EP260703a: EP-WXT detection of a fast X-ray transient
  54. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  55. GRB 260703A: Fermi GBM Final Localization
  56. GRB 260610B: VLA detection
  57. GRB 260623A: Glowbug gamma-ray detection
  58. GRB 260701A: Fermi GBM Final Real-time Localization
  59. EP260628a: EP-FXT follow-up observation
  60. GRB 260629A: Fermi GBM Final Real-time Localization
  61. EP260628a: EP-WXT detection of a fast X-ray transient
  62. GRB 260628A: Fermi GBM Final Real-time Localization
  63. EP260626a: EP-FXT follow-up observation
  64. EP260626a: Liverpool Telescope upper limits
  65. EP260626a: EP-WXT detection of a fast X-ray transient
  66. Konus-Wind detection of GRB 260623B / EP260623a
  67. EP260623a: TNG NIR afterglow detection
  68. MASS-Cube (GRID 2.0) detection of GRB 260616B
  69. Konus-Wind detection of GRB 260618B
  70. GRB 260624A: Fermi GBM Final Real-time Localization
  71. GRB 260617A: Glowbug gamma-ray detection of a short burst
  72. IPN triangulation of GRB 260605A
  73. EP260623a: Optical follow-up observations with Kinder
  74. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  75. GRB 260623A: Fermi GBM Final Real-time Localization
  76. EP260623a: TRT optical observations
  77. EP260623a: REM optical/NIR afterglow detection
  78. EP 260623a: COLIBRÍ optical observations
  79. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  80. EP260623a: Einstein Probe detection of an X-ray transient
  81. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  82. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  83. EP260618a: Liverpool Telescope optical observations
  84. GRB 260619A: NOT optical observations
  85. EP260618a: JinShan optical observations
  86. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  87. GRB 260619A: TRT optical counterpart confirmation
  88. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  89. GRB 260604B: 239Alferov CubeSat detection
  90. GRB 260604A: 239Alferov CubeSat detection
  91. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  92. Konus-Wind detection of GRB 260617A
  93. GRB 260616B: AstroSat CZTI detection
  94. GRB 260616A: AstroSat CZTI detection
  95. GRB 260616A: SVOM/GRM observation
  96. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  97. EP260618a: EP-FXT follow-up observation
  98. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 260616A: NuSTAR detection of prompt emission
  100. GRB 260614B: NuSTAR detection of prompt emission

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