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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"
  1. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  2. The EP-WXT trigger 01709274014 is likely a flaring star
  3. IceCube260704A: OHP/T193 optical observations
  4. GRB 260705A: LCO optical upper limits
  5. GRB 260704A: NOT optical upper limits
  6. GRB 260705C: Fermi GBM Final Localization
  7. GRB 260705B: Fermi GBM Final Real-time Localization
  8. Fermi GBM Sub-Threshold Detection of GRB 260705A
  9. GRB 260705A: SVOM detection of a burst
  10. GRB 260704A: EP-FXT follow-up observation
  11. GRB 260629A: SVOM/GRM observation of a short burst
  12. GRB 260629A: GECAM-A observation of a short burst
  13. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  14. GRB 260629A: AstroSat CZTI detection
  15. EP260703a: EP-FXT follow-up observation
  16. GRB 260704A: SVOM detection of a possible GRB
  17. GRB 260703B: Fermi GBM Final Localization
  18. EP260703a: EP-WXT detection of a fast X-ray transient
  19. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  20. Fermi trigger No 804738310: Global MASTER-Net observations report
  21. Fermi GRB 260703A: Global MASTER-Net observations report
  22. GRB 260703A: Fermi GBM Final Localization
  23. GRB 260610B: VLA detection
  24. GRB 260623A: Glowbug gamma-ray detection
  25. GRB 260614B: ATCA Radio Upper Limits
  26. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  27. Fermi trigger No 804552016: Global MASTER-Net observations report
  28. GRB 260701A: Fermi GBM Final Real-time Localization
  29. Fermi GBM trigger 804552016/260630945 is not a GRB
  30. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  31. EP260628a: EP-FXT follow-up observation
  32. GRB 260629A: Fermi GBM Final Real-time Localization
  33. Fermi GRB 260628A: Global MASTER-Net observations report
  34. EP260628a: EP-WXT detection of a fast X-ray transient
  35. GRB 260628A: Fermi GBM Final Real-time Localization
  36. The EP-WXT trigger 01709272671 is likely a flaring star
  37. EP260626a: further Liverpool Telescope optical upper limits
  38. EP260626a: EP-FXT follow-up observation
  39. EP260626a: COLIBRÍ optical upper limit
  40. EP260626a: Liverpool Telescope upper limits
  41. EP260626a: EP-WXT detection of a fast X-ray transient
  42. Konus-Wind detection of GRB 260623B / EP260623a
  43. EP260623a: TNG NIR afterglow detection
  44. GRB 260618A: Fermi GBM Observation
  45. MASS-Cube (GRID 2.0) detection of GRB 260616B
  46. EP260623a: FTW optical and NIR observations
  47. GRB 260619A: SVOM/ECLAIRs refined analysis
  48. EP260623a: Liverpool Telescope optical observations
  49. Fermi GBM trigger 804010507/260624677 is not a GRB
  50. Konus-Wind detection of GRB 260618B
  51. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  52. GRB 260624A: Fermi GBM Final Real-time Localization
  53. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  54. EP260623a: WINTER J-band observations
  55. GRB 260617A: Glowbug gamma-ray detection of a short burst
  56. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  57. IPN triangulation of GRB 260605A
  58. EP260623a: Optical follow-up observations with Kinder
  59. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  60. GRB 260623A: Fermi GBM Final Real-time Localization
  61. EP260623a: SVOM/VT optical observations
  62. EP260623a: TRT optical observations
  63. EP260623a: REM optical/NIR afterglow detection
  64. EP 260623a: COLIBRÍ optical observations
  65. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  66. EP260623a: OSIRIS+/GTC redshift z = 0.703
  67. EP260623a: Las Cumbres discovery of the optical counterpart
  68. EP260623a: Einstein Probe detection of an X-ray transient
  69. GRB 260614B: EP-FXT follow-up observation
  70. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  72. EP260618a: Liverpool Telescope optical observations
  73. GRB 260619A: NOT optical observations
  74. GRB 260618B: LCO optical observations
  75. The EP-WXT trigger 01709271197 is likely a flaring star
  76. EP260618a: JinShan optical observations
  77. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  78. GRB 260618B: Fermi GBM Observation
  79. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  80. GRB 260619A: TRT optical counterpart confirmation
  81. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  82. GRB 260604B: 239Alferov CubeSat detection
  83. GRB 260604A: 239Alferov CubeSat detection
  84. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  85. GRB 260619A: SVOM/VT optical counterpart confirmation
  86. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  87. GRB 260618B: SVOM/VT optical candidate
  88. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  89. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  90. Konus-Wind detection of GRB 260617A
  91. GRB 260616B: AstroSat CZTI detection
  92. GRB 260616A: AstroSat CZTI detection
  93. GRB 260616A: SVOM/GRM observation
  94. EP260618a: OHP/T193 optical observations
  95. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  96. GRB 260619A: Kilonova-Catcher optical upper limit
  97. EP260618a: EP-FXT follow-up observation
  98. EP260618a: LCO optical counterpart confirmation
  99. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  100. EP260618a: COLIBRÍ optical counterpart candidate

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