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

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