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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. GRB 260707A: Fermi GBM Final Real-time Localization
  2. The EP-WXT trigger 01709274151 is likely a flaring star
  3. The EP-WXT trigger 01709274141 is likely a flaring star
  4. GRB 260706A: Fermi GBM Observation
  5. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  6. IPN triangulation of GRB 260627A
  7. GRB 260705A: SVOM/ECLAIRs refined analysis
  8. GRB 260706A: SVOM detection of a burst
  9. GRB 260706A: Fermi GBM Final Real-time Localization
  10. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  11. The EP-WXT trigger 01709274014 is likely a flaring star
  12. IceCube260704A: OHP/T193 optical observations
  13. GRB 260705A: LCO optical upper limits
  14. GRB 260704A: NOT optical upper limits
  15. GRB 260705C: Fermi GBM Final Localization
  16. GRB 260705B: Fermi GBM Final Real-time Localization
  17. Fermi GBM Sub-Threshold Detection of GRB 260705A
  18. GRB 260705A: SVOM detection of a burst
  19. GRB 260704A: EP-FXT follow-up observation
  20. GRB 260629A: SVOM/GRM observation of a short burst
  21. GRB 260629A: GECAM-A observation of a short burst
  22. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  23. GRB 260629A: AstroSat CZTI detection
  24. EP260703a: EP-FXT follow-up observation
  25. GRB 260704A: SVOM detection of a possible GRB
  26. GRB 260703B: Fermi GBM Final Localization
  27. EP260703a: EP-WXT detection of a fast X-ray transient
  28. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  29. Fermi trigger No 804738310: Global MASTER-Net observations report
  30. Fermi GRB 260703A: Global MASTER-Net observations report
  31. GRB 260703A: Fermi GBM Final Localization
  32. GRB 260610B: VLA detection
  33. GRB 260623A: Glowbug gamma-ray detection
  34. GRB 260614B: ATCA Radio Upper Limits
  35. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  36. Fermi trigger No 804552016: Global MASTER-Net observations report
  37. GRB 260701A: Fermi GBM Final Real-time Localization
  38. Fermi GBM trigger 804552016/260630945 is not a GRB
  39. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  40. EP260628a: EP-FXT follow-up observation
  41. GRB 260629A: Fermi GBM Final Real-time Localization
  42. Fermi GRB 260628A: Global MASTER-Net observations report
  43. EP260628a: EP-WXT detection of a fast X-ray transient
  44. GRB 260628A: Fermi GBM Final Real-time Localization
  45. The EP-WXT trigger 01709272671 is likely a flaring star
  46. EP260626a: further Liverpool Telescope optical upper limits
  47. EP260626a: EP-FXT follow-up observation
  48. EP260626a: COLIBRÍ optical upper limit
  49. EP260626a: Liverpool Telescope upper limits
  50. EP260626a: EP-WXT detection of a fast X-ray transient
  51. Konus-Wind detection of GRB 260623B / EP260623a
  52. EP260623a: TNG NIR afterglow detection
  53. GRB 260618A: Fermi GBM Observation
  54. MASS-Cube (GRID 2.0) detection of GRB 260616B
  55. EP260623a: FTW optical and NIR observations
  56. GRB 260619A: SVOM/ECLAIRs refined analysis
  57. EP260623a: Liverpool Telescope optical observations
  58. Fermi GBM trigger 804010507/260624677 is not a GRB
  59. Konus-Wind detection of GRB 260618B
  60. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  61. GRB 260624A: Fermi GBM Final Real-time Localization
  62. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  63. EP260623a: WINTER J-band observations
  64. GRB 260617A: Glowbug gamma-ray detection of a short burst
  65. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  66. IPN triangulation of GRB 260605A
  67. EP260623a: Optical follow-up observations with Kinder
  68. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  69. GRB 260623A: Fermi GBM Final Real-time Localization
  70. EP260623a: SVOM/VT optical observations
  71. EP260623a: TRT optical observations
  72. EP260623a: REM optical/NIR afterglow detection
  73. EP 260623a: COLIBRÍ optical observations
  74. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  75. EP260623a: OSIRIS+/GTC redshift z = 0.703
  76. EP260623a: Las Cumbres discovery of the optical counterpart
  77. EP260623a: Einstein Probe detection of an X-ray transient
  78. GRB 260614B: EP-FXT follow-up observation
  79. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  80. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  81. EP260618a: Liverpool Telescope optical observations
  82. GRB 260619A: NOT optical observations
  83. GRB 260618B: LCO optical observations
  84. The EP-WXT trigger 01709271197 is likely a flaring star
  85. EP260618a: JinShan optical observations
  86. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  87. GRB 260618B: Fermi GBM Observation
  88. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  89. GRB 260619A: TRT optical counterpart confirmation
  90. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  91. GRB 260604B: 239Alferov CubeSat detection
  92. GRB 260604A: 239Alferov CubeSat detection
  93. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  94. GRB 260619A: SVOM/VT optical counterpart confirmation
  95. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  96. GRB 260618B: SVOM/VT optical candidate
  97. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  98. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  99. Konus-Wind detection of GRB 260617A
  100. GRB 260616B: AstroSat CZTI detection

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