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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. IPN triangulation of GRB 260627A
  2. GRB 260705A: SVOM/ECLAIRs refined analysis
  3. GRB 260706A: SVOM detection of a burst
  4. GRB 260706A: Fermi GBM Final Real-time Localization
  5. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  6. The EP-WXT trigger 01709274014 is likely a flaring star
  7. IceCube260704A: OHP/T193 optical observations
  8. GRB 260705A: LCO optical upper limits
  9. GRB 260704A: NOT optical upper limits
  10. GRB 260705C: Fermi GBM Final Localization
  11. GRB 260705B: Fermi GBM Final Real-time Localization
  12. Fermi GBM Sub-Threshold Detection of GRB 260705A
  13. GRB 260705A: SVOM detection of a burst
  14. GRB 260704A: EP-FXT follow-up observation
  15. GRB 260629A: SVOM/GRM observation of a short burst
  16. GRB 260629A: GECAM-A observation of a short burst
  17. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  18. GRB 260629A: AstroSat CZTI detection
  19. EP260703a: EP-FXT follow-up observation
  20. GRB 260704A: SVOM detection of a possible GRB
  21. GRB 260703B: Fermi GBM Final Localization
  22. EP260703a: EP-WXT detection of a fast X-ray transient
  23. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  24. Fermi trigger No 804738310: Global MASTER-Net observations report
  25. Fermi GRB 260703A: Global MASTER-Net observations report
  26. GRB 260703A: Fermi GBM Final Localization
  27. GRB 260610B: VLA detection
  28. GRB 260623A: Glowbug gamma-ray detection
  29. GRB 260614B: ATCA Radio Upper Limits
  30. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  31. Fermi trigger No 804552016: Global MASTER-Net observations report
  32. GRB 260701A: Fermi GBM Final Real-time Localization
  33. Fermi GBM trigger 804552016/260630945 is not a GRB
  34. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  35. EP260628a: EP-FXT follow-up observation
  36. GRB 260629A: Fermi GBM Final Real-time Localization
  37. Fermi GRB 260628A: Global MASTER-Net observations report
  38. EP260628a: EP-WXT detection of a fast X-ray transient
  39. GRB 260628A: Fermi GBM Final Real-time Localization
  40. The EP-WXT trigger 01709272671 is likely a flaring star
  41. EP260626a: further Liverpool Telescope optical upper limits
  42. EP260626a: EP-FXT follow-up observation
  43. EP260626a: COLIBRÍ optical upper limit
  44. EP260626a: Liverpool Telescope upper limits
  45. EP260626a: EP-WXT detection of a fast X-ray transient
  46. Konus-Wind detection of GRB 260623B / EP260623a
  47. EP260623a: TNG NIR afterglow detection
  48. GRB 260618A: Fermi GBM Observation
  49. MASS-Cube (GRID 2.0) detection of GRB 260616B
  50. EP260623a: FTW optical and NIR observations
  51. GRB 260619A: SVOM/ECLAIRs refined analysis
  52. EP260623a: Liverpool Telescope optical observations
  53. Fermi GBM trigger 804010507/260624677 is not a GRB
  54. Konus-Wind detection of GRB 260618B
  55. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  56. GRB 260624A: Fermi GBM Final Real-time Localization
  57. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  58. EP260623a: WINTER J-band observations
  59. GRB 260617A: Glowbug gamma-ray detection of a short burst
  60. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  61. IPN triangulation of GRB 260605A
  62. EP260623a: Optical follow-up observations with Kinder
  63. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  64. GRB 260623A: Fermi GBM Final Real-time Localization
  65. EP260623a: SVOM/VT optical observations
  66. EP260623a: TRT optical observations
  67. EP260623a: REM optical/NIR afterglow detection
  68. EP 260623a: COLIBRÍ optical observations
  69. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  70. EP260623a: OSIRIS+/GTC redshift z = 0.703
  71. EP260623a: Las Cumbres discovery of the optical counterpart
  72. EP260623a: Einstein Probe detection of an X-ray transient
  73. GRB 260614B: EP-FXT follow-up observation
  74. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  75. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  76. EP260618a: Liverpool Telescope optical observations
  77. GRB 260619A: NOT optical observations
  78. GRB 260618B: LCO optical observations
  79. The EP-WXT trigger 01709271197 is likely a flaring star
  80. EP260618a: JinShan optical observations
  81. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  82. GRB 260618B: Fermi GBM Observation
  83. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB 260619A: TRT optical counterpart confirmation
  85. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  86. GRB 260604B: 239Alferov CubeSat detection
  87. GRB 260604A: 239Alferov CubeSat detection
  88. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  89. GRB 260619A: SVOM/VT optical counterpart confirmation
  90. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  91. GRB 260618B: SVOM/VT optical candidate
  92. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  93. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  94. Konus-Wind detection of GRB 260617A
  95. GRB 260616B: AstroSat CZTI detection
  96. GRB 260616A: AstroSat CZTI detection
  97. GRB 260616A: SVOM/GRM observation
  98. EP260618a: OHP/T193 optical observations
  99. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  100. GRB 260619A: Kilonova-Catcher optical upper limit

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