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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 01709274151 is likely a flaring star
  2. The EP-WXT trigger 01709274141 is likely a flaring star
  3. GRB 260706A: Fermi GBM Observation
  4. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  5. IPN triangulation of GRB 260627A
  6. GRB 260705A: SVOM/ECLAIRs refined analysis
  7. GRB 260706A: SVOM detection of a burst
  8. GRB 260706A: Fermi GBM Final Real-time Localization
  9. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  10. The EP-WXT trigger 01709274014 is likely a flaring star
  11. IceCube260704A: OHP/T193 optical observations
  12. GRB 260705A: LCO optical upper limits
  13. GRB 260704A: NOT optical upper limits
  14. GRB 260705C: Fermi GBM Final Localization
  15. GRB 260705B: Fermi GBM Final Real-time Localization
  16. Fermi GBM Sub-Threshold Detection of GRB 260705A
  17. GRB 260705A: SVOM detection of a burst
  18. GRB 260704A: EP-FXT follow-up observation
  19. GRB 260629A: SVOM/GRM observation of a short burst
  20. GRB 260629A: GECAM-A observation of a short burst
  21. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  22. GRB 260629A: AstroSat CZTI detection
  23. EP260703a: EP-FXT follow-up observation
  24. GRB 260704A: SVOM detection of a possible GRB
  25. GRB 260703B: Fermi GBM Final Localization
  26. EP260703a: EP-WXT detection of a fast X-ray transient
  27. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  28. Fermi trigger No 804738310: Global MASTER-Net observations report
  29. Fermi GRB 260703A: Global MASTER-Net observations report
  30. GRB 260703A: Fermi GBM Final Localization
  31. GRB 260610B: VLA detection
  32. GRB 260623A: Glowbug gamma-ray detection
  33. GRB 260614B: ATCA Radio Upper Limits
  34. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  35. Fermi trigger No 804552016: Global MASTER-Net observations report
  36. GRB 260701A: Fermi GBM Final Real-time Localization
  37. Fermi GBM trigger 804552016/260630945 is not a GRB
  38. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  39. EP260628a: EP-FXT follow-up observation
  40. GRB 260629A: Fermi GBM Final Real-time Localization
  41. Fermi GRB 260628A: Global MASTER-Net observations report
  42. EP260628a: EP-WXT detection of a fast X-ray transient
  43. GRB 260628A: Fermi GBM Final Real-time Localization
  44. The EP-WXT trigger 01709272671 is likely a flaring star
  45. EP260626a: further Liverpool Telescope optical upper limits
  46. EP260626a: EP-FXT follow-up observation
  47. EP260626a: COLIBRÍ optical upper limit
  48. EP260626a: Liverpool Telescope upper limits
  49. EP260626a: EP-WXT detection of a fast X-ray transient
  50. Konus-Wind detection of GRB 260623B / EP260623a
  51. EP260623a: TNG NIR afterglow detection
  52. GRB 260618A: Fermi GBM Observation
  53. MASS-Cube (GRID 2.0) detection of GRB 260616B
  54. EP260623a: FTW optical and NIR observations
  55. GRB 260619A: SVOM/ECLAIRs refined analysis
  56. EP260623a: Liverpool Telescope optical observations
  57. Fermi GBM trigger 804010507/260624677 is not a GRB
  58. Konus-Wind detection of GRB 260618B
  59. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  60. GRB 260624A: Fermi GBM Final Real-time Localization
  61. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  62. EP260623a: WINTER J-band observations
  63. GRB 260617A: Glowbug gamma-ray detection of a short burst
  64. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  65. IPN triangulation of GRB 260605A
  66. EP260623a: Optical follow-up observations with Kinder
  67. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  68. GRB 260623A: Fermi GBM Final Real-time Localization
  69. EP260623a: SVOM/VT optical observations
  70. EP260623a: TRT optical observations
  71. EP260623a: REM optical/NIR afterglow detection
  72. EP 260623a: COLIBRÍ optical observations
  73. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  74. EP260623a: OSIRIS+/GTC redshift z = 0.703
  75. EP260623a: Las Cumbres discovery of the optical counterpart
  76. EP260623a: Einstein Probe detection of an X-ray transient
  77. GRB 260614B: EP-FXT follow-up observation
  78. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  79. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  80. EP260618a: Liverpool Telescope optical observations
  81. GRB 260619A: NOT optical observations
  82. GRB 260618B: LCO optical observations
  83. The EP-WXT trigger 01709271197 is likely a flaring star
  84. EP260618a: JinShan optical observations
  85. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  86. GRB 260618B: Fermi GBM Observation
  87. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  88. GRB 260619A: TRT optical counterpart confirmation
  89. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  90. GRB 260604B: 239Alferov CubeSat detection
  91. GRB 260604A: 239Alferov CubeSat detection
  92. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  93. GRB 260619A: SVOM/VT optical counterpart confirmation
  94. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  95. GRB 260618B: SVOM/VT optical candidate
  96. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  97. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  98. Konus-Wind detection of GRB 260617A
  99. GRB 260616B: AstroSat CZTI detection
  100. GRB 260616A: AstroSat CZTI detection

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