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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"

32485 results found.

  1. IceCube260704A: OHP/T193 optical observations
  2. GRB 260705A: LCO optical upper limits
  3. GRB 260704A: NOT optical upper limits
  4. Fermi GBM Sub-Threshold Detection of GRB 260705A
  5. GRB 260704A: EP-FXT follow-up observation
  6. GRB 260629A: SVOM/GRM observation of a short burst
  7. GRB 260629A: GECAM-A observation of a short burst
  8. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  9. GRB 260629A: AstroSat CZTI detection
  10. EP260703a: EP-FXT follow-up observation
  11. Fermi GRB 260703A: Global MASTER-Net observations report
  12. GRB 260610B: VLA detection
  13. GRB 260623A: Glowbug gamma-ray detection
  14. GRB 260614B: ATCA Radio Upper Limits
  15. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  16. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  17. EP260628a: EP-FXT follow-up observation
  18. Fermi GRB 260628A: Global MASTER-Net observations report
  19. EP260626a: further Liverpool Telescope optical upper limits
  20. EP260626a: EP-FXT follow-up observation
  21. EP260626a: COLIBRÍ optical upper limit
  22. EP260626a: Liverpool Telescope upper limits
  23. Konus-Wind detection of GRB 260623B / EP260623a
  24. EP260623a: TNG NIR afterglow detection
  25. GRB 260618A: Fermi GBM Observation
  26. MASS-Cube (GRID 2.0) detection of GRB 260616B
  27. EP260623a: FTW optical and NIR observations
  28. GRB 260619A: SVOM/ECLAIRs refined analysis
  29. EP260623a: Liverpool Telescope optical observations
  30. Konus-Wind detection of GRB 260618B
  31. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  32. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  33. EP260623a: WINTER J-band observations
  34. GRB 260617A: Glowbug gamma-ray detection of a short burst
  35. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  36. IPN triangulation of GRB 260605A
  37. EP260623a: Optical follow-up observations with Kinder
  38. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  39. EP260623a: SVOM/VT optical observations
  40. EP260623a: TRT optical observations
  41. EP260623a: REM optical/NIR afterglow detection
  42. EP 260623a: COLIBRÍ optical observations
  43. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  44. EP260623a: OSIRIS+/GTC redshift z = 0.703
  45. EP260623a: Las Cumbres discovery of the optical counterpart
  46. GRB 260614B: EP-FXT follow-up observation
  47. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  48. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  49. EP260618a: Liverpool Telescope optical observations
  50. GRB 260619A: NOT optical observations
  51. GRB 260618B: LCO optical observations
  52. EP260618a: JinShan optical observations
  53. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  54. GRB 260618B: Fermi GBM Observation
  55. GRB 260619A: TRT optical counterpart confirmation
  56. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  57. GRB 260604B: 239Alferov CubeSat detection
  58. GRB 260604A: 239Alferov CubeSat detection
  59. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  60. GRB 260619A: SVOM/VT optical counterpart confirmation
  61. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  62. GRB 260618B: SVOM/VT optical candidate
  63. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  64. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  65. Konus-Wind detection of GRB 260617A
  66. GRB 260616B: AstroSat CZTI detection
  67. GRB 260616A: AstroSat CZTI detection
  68. GRB 260616A: SVOM/GRM observation
  69. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  70. GRB 260619A: Kilonova-Catcher optical upper limit
  71. EP260618a: EP-FXT follow-up observation
  72. EP260618a: LCO optical counterpart confirmation
  73. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  74. EP260618a: COLIBRÍ optical counterpart candidate
  75. GRB 260616A: NuSTAR detection of prompt emission
  76. GRB 260614B: NuSTAR detection of prompt emission
  77. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  78. GRB 260618B: Fermi-LAT detection
  79. IPN triangulation of GRB 260617A (short)
  80. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  81. GRB 260616A: Insight-HXMT detection
  82. EP260618a: EP-WXT detection of an X-ray transient
  83. GRB 260610B: AbAO optical observations
  84. EP260616a/GRB 260616B: EP-FXT follow-up observation
  85. GRB 260506B: cubesat Avion detection
  86. GRB 260616C: GECAM-B observation of a burst
  87. GRB 260616A: Fermi GBM Observation
  88. GRB 260617A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  89. Konus-Wind detection of GRB 260616B/EP260616a
  90. Konus-Wind detection of GRB 260616A
  91. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  92. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  93. GRB 260616A: GECAM-B observation
  94. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  95. GRB 260429A: cubesat Avion detection
  96. GRB 260616A: Fermi-LAT detection
  97. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  98. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  99. GRB 260614A: AstroSat CZTI detection
  100. EP260616a: EP-WXT detection of a fast X-ray transient

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