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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"

43623 results found.

  1. GRB 260705B: Fermi GBM Final Real-time Localization
  2. Fermi GBM Sub-Threshold Detection of GRB 260705A
  3. GRB 260705A: SVOM detection of a burst
  4. GRB 260704A: EP-FXT follow-up observation
  5. GRB 260629A: SVOM/GRM observation of a short burst
  6. GRB 260629A: GECAM-A observation of a short burst
  7. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  8. GRB 260629A: AstroSat CZTI detection
  9. EP260703a: EP-FXT follow-up observation
  10. GRB 260704A: SVOM detection of a possible GRB
  11. GRB 260703B: Fermi GBM Final Localization
  12. EP260703a: EP-WXT detection of a fast X-ray transient
  13. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  14. Fermi trigger No 804738310: Global MASTER-Net observations report
  15. Fermi GRB 260703A: Global MASTER-Net observations report
  16. GRB 260703A: Fermi GBM Final Localization
  17. GRB 260610B: VLA detection
  18. GRB 260623A: Glowbug gamma-ray detection
  19. GRB 260614B: ATCA Radio Upper Limits
  20. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  21. Fermi trigger No 804552016: Global MASTER-Net observations report
  22. GRB 260701A: Fermi GBM Final Real-time Localization
  23. Fermi GBM trigger 804552016/260630945 is not a GRB
  24. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  25. EP260628a: EP-FXT follow-up observation
  26. GRB 260629A: Fermi GBM Final Real-time Localization
  27. Fermi GRB 260628A: Global MASTER-Net observations report
  28. EP260628a: EP-WXT detection of a fast X-ray transient
  29. GRB 260628A: Fermi GBM Final Real-time Localization
  30. The EP-WXT trigger 01709272671 is likely a flaring star
  31. EP260626a: further Liverpool Telescope optical upper limits
  32. EP260626a: EP-FXT follow-up observation
  33. EP260626a: COLIBRÍ optical upper limit
  34. EP260626a: Liverpool Telescope upper limits
  35. EP260626a: EP-WXT detection of a fast X-ray transient
  36. Konus-Wind detection of GRB 260623B / EP260623a
  37. EP260623a: TNG NIR afterglow detection
  38. GRB 260618A: Fermi GBM Observation
  39. MASS-Cube (GRID 2.0) detection of GRB 260616B
  40. EP260623a: FTW optical and NIR observations
  41. GRB 260619A: SVOM/ECLAIRs refined analysis
  42. EP260623a: Liverpool Telescope optical observations
  43. Fermi GBM trigger 804010507/260624677 is not a GRB
  44. Konus-Wind detection of GRB 260618B
  45. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  46. GRB 260624A: Fermi GBM Final Real-time Localization
  47. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  48. EP260623a: WINTER J-band observations
  49. GRB 260617A: Glowbug gamma-ray detection of a short burst
  50. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  51. IPN triangulation of GRB 260605A
  52. EP260623a: Optical follow-up observations with Kinder
  53. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  54. GRB 260623A: Fermi GBM Final Real-time Localization
  55. EP260623a: SVOM/VT optical observations
  56. EP260623a: TRT optical observations
  57. EP260623a: REM optical/NIR afterglow detection
  58. EP 260623a: COLIBRÍ optical observations
  59. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  60. EP260623a: OSIRIS+/GTC redshift z = 0.703
  61. EP260623a: Las Cumbres discovery of the optical counterpart
  62. EP260623a: Einstein Probe detection of an X-ray transient
  63. GRB 260614B: EP-FXT follow-up observation
  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. EP260618a: Liverpool Telescope optical observations
  67. GRB 260619A: NOT optical observations
  68. GRB 260618B: LCO optical observations
  69. The EP-WXT trigger 01709271197 is likely a flaring star
  70. EP260618a: JinShan optical observations
  71. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  72. GRB 260618B: Fermi GBM Observation
  73. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  74. GRB 260619A: TRT optical counterpart confirmation
  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/VT optical counterpart confirmation
  80. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  81. GRB 260618B: SVOM/VT optical candidate
  82. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  83. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  84. Konus-Wind detection of GRB 260617A
  85. GRB 260616B: AstroSat CZTI detection
  86. GRB 260616A: AstroSat CZTI detection
  87. GRB 260616A: SVOM/GRM observation
  88. EP260618a: OHP/T193 optical observations
  89. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  90. GRB 260619A: Kilonova-Catcher optical upper limit
  91. EP260618a: EP-FXT follow-up observation
  92. EP260618a: LCO optical counterpart confirmation
  93. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  94. EP260618a: COLIBRÍ optical counterpart candidate
  95. GRB 260616A: NuSTAR detection of prompt emission
  96. GRB 260614B: NuSTAR detection of prompt emission
  97. GRB 260619A: SVOM possible detection of a faint burst
  98. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 260618B: Fermi-LAT detection
  100. IPN triangulation of GRB 260617A (short)

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